GSM BASED TEMPERATURE MEASUREMENT AND THERMOREGULATION OF PRETERM INFANT IN NICU

Transcription

1 CHAPTER 3 GSM BASED TEMPERATURE MEASUREMENT AND THERMOREGULATION OF PRETERM INFANT IN NICU 3.1 Introduction Temperature is the physical quantity of heat which is subjected to the material characteristic that enforce the environment to undergo its effect. The action of measurement is normally done by the Thermometer wherein the material s thermal radiations are mediated for the detection by the particle s intensity of colliding velocity. Thermal energy is the total energy of all the particles in the particular material. Temperature is a measure of average energy of the particles in the particular material. This intensity of velocity of radiations are taken into consideration for the calibration guidance to set measuring point like Kelvin, Celsius and Fahrenheit. One of the most real world physical parameter systems need to measure is temperature. From manufacture of steel to the fabrication of the semiconductors, many industrial processes depends on temperature.some electronic devices such as computers that monitors its CPU or a power drive IC need to measure their own temperature. Temperature sensors have been developed based on different temperature dependent physical phenomenon that include thermal expansions, electrical resistance and thermal radiation temperature sensors vary from simple liquid in glass thermometer to sophisticated and state of cost thermal imaging thermometers. Some temperature sensors generate digital signals readily used for online monitoring and automatic temperature control purposes. Temperature also plays an important role in almost all fields of science and Technology including physics, geology, chemistry, atmospheric sciences, process, biology and bio-medical systems. Many physical properties of material including the density, phase, solubility, vapor pressure and electrical conductivity depend on temperature. Temperature also plays vital role in determining the rate and extent to which chemical reaction occur. 91

2 Modern scientific thermometers and temperature scales are used for temperature measurements goes back at least as far as the early 18 th century. Ole Christensen Roemer developed a thermometer and a scale which are lately adapted by Rabriel Fahrenheit. Fahrenheit scale is still in use, alongside the Celsius scale and Kelvin scale. Since temperature only a few degrees higher can result in harmful reactions with sensors consequences, the human body has several elaborate mechanisms for maintaining the temperature at 310K. Temperature also controls the type and quality of thermal radiation emitted from a surface. The tungsten filament in the incandescent light bulb is electrically heated to a temperature at which significant quantities of visible light radiation are emitted. The entire scientific world measures temperature using the Celsius scale and the thermodynamics temperature using the Kelvin scale. Many engineering fields in the U.S, notably high tech and U.S federal specifications also use the kelvin and Celsius scale. Temperature is measured with thermometers that may be calibrated to variety of temperature scales. The basic unit of temperature in the international system of units [SI] is the kelvin [k]. The kelvin and Celsius scales are defined by two points: absolute zero and the triple point of Lima standard Mean ocean water. Absolute zero is defined as being precisely 0K and At absolute zero, all the particles compressing matter having kinetic motion ceases and are at complete rest in the classic sense TEMERATURE SCALE Temperature measurement is carried out on three scales namely kelvin, Celsius and Fahrenheit. In various parts of the world, different scales are used depending upon the ease with which they use. Fahrenheit scale is widely used in the United States. While in India, Celsius scale is widely used. The general equation that can be used to convert the Fahrenheit scale to Celsius scale is given as C = (F-32)*5/9 The both the scales of Fahrenheit and Celsius are used in the present study. 92

3 3.2 TEMPERATURE MEASURMENT DEVICES Temperature can be measured by many methods using different types of sensors. some of the more common are described in this section Thermistors Thermistor is a temperature measuring device whose resistance varies with temperature and this property is used to measure the temperature. Generally, thermistors are made up of semiconducting materials. Temperature coefficients of thermistors can be positive or negative, mostly negative coefficient thermistors are used. Negative temperature coefficient implies that the resistance decreases with increasing temperatures. Thermistors cannot be used for high temperature ranges, usually thermistors work within a limited temperature ranging -90 C and 130 C. Thermistors are usually small in size which gives it ability to sense temperature changes quickly but this also leads the thermistors move susceptible to self-healthy errors as shown in Figure 3.1. Figure 3.1: NTC Thermistors Thermistors are fragile compared to RTD or thermocouples, so they must be carefully monitored to avoid unnecessary damages Thermocouple A thermocouple is made up of two dissimilar metals to form a junction, which produces a tiny voltage difference between them when heated. The voltage depends on 93

4 the thermocouple combinations of the metals. The three most commonly used thermocouple combinations are Iron-Constantan (type J), Copper-Constantan (type T) and Chromel-Alumel (type K). Thermocouple is the most widely used temperature measuring devices in the processing industries as it provides a good balance of accuracy, reliability and cost. Thermocouple is as shown in figure 3.2. Thermocouple works on the principle of seebeck effect or thermoelectric effect. The seebeck effect was first discovered by a German physicist Thomas Johann Seebeck in the year 1821, he observed that any conductor subjected to a thermal gradient, and then there would be a generation of external voltages. The magnitude of the voltage depends on the metal materials in use and so a non-zero voltage can be measured if two dissimilar metals are used. Figure 3.2: Thermocouple To measure the temperature at any point, temperature of the reference metal must be determined. So two main strategies are used for determining the reference metal temperature IC sensors IC (Integrated Circuits) temperature sensors are semiconducting devices whose manufacturing is similar to that of modern day electronics semiconductor devices like microprocessors. Usually thousands of semiconductor devices are fabricated upon thin 94

5 silicon wafer to obtain an IC temperature sensor. Popularly used IC sensors are AD590 and LM35. The design of these IC sensors is based on the fact that a semiconductor diode has a defined voltage vs. current characteristics, where the voltage of the semiconductor diode material is temperature sensitive. So using this methodology, we can measure the temperature. IC sensors are available in moderately small sizes, which works in temperature ranging from -40 C and +120 C, with fairly accurate temperature readings provided that they are properly calibrated. Compared to RTD s and thermocouples, the working of an IC sensor is more robust. IC sensors are ideal for embedded applications as they are installed within the equipment itself. IC sensors enables interfacing simple with other electronic devices like regulators, digital signal processors, amplifiers, microcontrollers, etc. IC sensors cannot measure high temperatures and doesn t have good thermal contact with external surfaces. Types of semiconductor sensors 1. Voltage output temperature sensors 2. Current output temperature sensors 3. Digital output temperature sensors 4. Resistance output silicon temperature sensors 5. Diode temperature sensors Optical Pyrometers These are also known as brightness pyrometers. Usually pyrometers are used to measure high temperatures. The word pyrometers are derived from the Greek word i.e. pyro which means fire and meter which stands for measure. Optical pyrometer uses a non-contacting device that intercepts and measures thermal radiations. This thermal radiation is used to determine the temperature of a given object s surface. 95

6 It had a optical system and a detector. Optical system focuses the thermal radiation onto the detector. Output of the detector i.e. the temperature is related to the thermal radiation or irradiance j* of the object s surface through Stefan-Boltzmann law. As the optical pyrometer is based on the light intensity, it can be used only in applications where the temperature is greater than 700 C and also optical pyrometers cannot be sued for obtaining continuous values of temperatures at small intervals. 3.3 Thermoregulation Thermoregulation is the process that allows the human body to maintain its core internal temperature. The state of having an even internal temperature is called homeostasis. All thermoregulation mechanisms are designed to return the body to homeostasis. Thermoregulation is also the ability to balance heat production and heat loss in order to maintain body temperature within the healthy, safe temperature which varies between 98 F (37 C) and 100 F (37.8 C) Human Thermoregulation Humans are homoeothermic or capable of regulating their core temperature within a narrow limit. Control of body temperature is achieved by a complex system via negative feedback, which includes an important balance between heat loss and heat gain is as shown in figure 3.3. Figure 3.3: Balance between Heat Production & Heat Loss 96

7 When exposed to a cold environment, human body temperature decreases, and peripheral and central thermo receptors detect change [1]. The thermoregulatory system of humans consists of these thermal sensors, afferent pathways, an integration system in the central nervous system, efferent pathways, and target organs that control heat generation and transfer is as shown in figure 3.4. Heat sensors in the brain called the hypothalamus controls thermoregulation. It issues instructions to your muscles, organs, glands, and nervous system when it senses your core internal temperature is becoming too low or too high. When brain receives a temperature warning from body, it sends signals to various organs and body systems, which try to slow or increase heat production. Figure 3.4: Thermoregulation in Human Infant Thermoregulation In adults, the immediate responses to a cold body temperature are peripheral vasoconstriction to diminish heat loss, inhibition of sweating, and initiation of shivering, with a resultant increase in heat production [2]. The effector mechanisms of skeletal muscle stimulation are minimal in infants, so infants do not shiver in response to a cold environment. Therefore, vasoconstriction is the main result of activation of peripheral skin receptors. 97

8 3.3.3 Nonshivering Thermogenesis Nonshivering thermogenesis is the main mechanism in neonates to produce heat through metabolic activity is as shown in figure 3.5. The primary source of heat production in the neonate. It is the production of heat by metabolism of brown fat Brown fat (deposited after 28 weeks gestation principally around the scapulae, kidneys, adrenals, neck and axilla) is a thermo genic organ unique neonate. Figure 3.5: Metabolic Heat Production in the Infant A major increase in thermogenin occurs at 32 weeks gestational age, approximately the time when a neonate can use nonshivering thermogenesis to generate heat effectively. The enzyme 5 /3 -monodeiodinase is active at 25 weeks gestational age, shows a major increase in amount at 32 weeks gestational age, and increases fourfold by term. Low levels of thermogenin and 5 /3 -monodeiodinase before 32 weeks are the probable causes of ineffective nonshivering thermogenesis in Extremely Low Birth Weight (ELBW) infants. Brown fat metabolism is inefficient in ELBW infants due to extreme immaturity and may not produce enough heat to prevent body temperature from falling. Because oxygen is needed to produce heat, oxygenation of the ELBW infant during cold stress may be decreased. Decreased oxygenation, increased acidosis, decreased blood glucose, 98

9 and increased heart rate due to cold stress can lead to increased morbidity and mortality. Thus, thermoregulation continues to be one of the primary priorities of nursing care for ELBW infants. 3.4 Heat Loss in the Neonatal Period Extremely low birth weight infants lose heat during birth and stabilization in the delivery room, transfer to the NICU, and stabilization procedures in the NICU. Understanding the ways in which these infants lose heat from their bodies is important in order to develop nursing interventions to prevent cold stress. Human thermoregulation attempts to keep body temperature in a steady state, in which thermogenesis (heat production) equals heat loss. The rate of heat loss depends on how rapidly heat is transferred from the inner body to the skin and how fast heat can be transferred from the skin to the environment. The skin, along with subcutaneous tissues and fat, acts as an insulator for the body. Fat conducts heat only one third as readily as other body tissues. Skin transfers heat to the environment by way of radiation, conduction, convection, and evaporation Methods of heat loss in Infants Heat loss of infants by various methods is as shown in Table 3.1. Heat loss in Infants is explained below EVAPORATION heat loss through wet skin. For infants 25 to 27 weeks gestational age in dry environments, evaporative heat loss is the major form of heat loss during the first 10 days of life. The transepidermal water loss in infants was inversely correlated with gestational age, with infants born at 25 weeks gestational age losing 15 times more water than term infants, because more immature preterm infants have thinner skin. These high evaporative heat losses in preterm infants during the first few hours and days of life gradually decrease with advancing postnatal age, most likely because of skin maturation. If infants are kept in an environment with 60% humidity, evaporative heat loss is much lower. 99

10 CONVECTION heat loss from cooler air circulating around warmer skin particularly when exposed. If the infant's body surface is warmer than the surrounding air, heat is first conducted into the air and then swept away by convective air currents. Convection is the source of heat loss when an infant is carried from the mother on the delivery room table through the cool air to the radiant warmer table. CONDUCTION heat loss through direct contact with a cold surface (e.g. scales, unwarmed mattress). Heat transfers by conduction occur when the skin is in contact with a surface of a different temperature. Heat moves from infant skin surface molecules to the molecules of another surface (air, water, or solid surface such as mattress) as they collide. In the NICU, conductive heat gain or loss is minimized by positioning infants on prewarmed surfaces. RADIATION heat loss from heat radiating towards a cooler surface (e.g. a cold window, wall or incubator wall) Table 3.1: Heat loss by various methods 3.5 Necessity for Temperature Measurement and Thermoregulation The rate of heat loss is proportional to the temperature difference between the skin and the radiating body. Heat may be lost from the infant's body to a nearby cold wall, or heat may be gained by the skin from a heat lamp near the infant. In infants older 100

11 than 28 weeks gestational age, heat loss from radiation is the most important route of heat transfer from birth onward. Radiative heat losses are initially low in ELBW infants but gradually increase with age and become the most important route of heat transfer after the first postnatal week. Premature infants, although born too soon, are not necessarily ill. The immature systems and organs of the preterm neonate require support to survive outside the womb and to overcome the related problems. These problems can involve: the lungs (unable to sustain their own respiratory function), immune system (susceptible to infections), the liver (a high percentage of premature infants become jaundiced), gastrointestinal system (unable to tolerate feeds and have prolonged periods of nothing by mouth), eyes (risk of retinopathy of prematurity), and the brain (immature vessels which are very fragile and are at risk from intraventricular hemorrhages and apnoea resulting from an immature central nervous system). Full term infants on the other hand encounter a different set of challenges ranging from birth asphyxia (a lack of oxygen during delivery), congenital abnormalities (this can include heart, brain, gastrointestinal, limbs and spine), birth trauma (injuries from birth, although very rare), jaundice, infection, and low birth weight. One of the main problems facing sick term and preterm infants is thermoregulation; or the need to keep the body warm. As they are very sensitive and usually suffers with hypothermia and hyperthermia [3] Hypothermia or Cold Stress Hypothermia is Infants or Neonate s body core temperature drops below < 35 to 35.5 C that required for normal metabolism and body functions. Hypothermia also may be caused by pathologic conditions that impair thermoregulation (e.g., sepsis, intracranial hemorrhage). Moderate hypothermia (>32 to < 36 C) Skin-to-skin contact should be in a warm room and warm bed. Warmer /Incubator may be used. Continue rewarming till temperature reaches normal range. Monitor every minutes. 101

12 Severe hypothermia (<32 C) Use air heated incubator (air temp C) or manually operated radiant warmer or thermostatically controlled heated mattress set at C. Once baby's temperature reaches 34 C the rewarming process should be slowed down Effects of Hypothermia A variety of physiological processes contribute to this harmful effect. Infants' oxygen consumption has been found to increase in response to hypothermia because of the energy demands of nonshivering thermogenesis. Although oxygen consumption has not been evaluated in ELBW infants because their tidal volumes are too low for accurate measurement, increased oxygen consumption can lead to acidosis and hypoglycemia in larger infants. Hypothermia may also lead to a fall in systemic arterial pressure, decreased plasma volume, decreased cardiac output, and increased peripheral resistance. If left unchecked, these conditions can lead to permanent tissue damage, brain damage, or death Hypothermia Treatment Hypothermia is treated by re warming in an incubator or under a radiant warmer. The neonate should be monitored and treated as needed for hypoglycemia, hypoxemia, and apnea. Underlying conditions such as sepsis or intracranial hemorrhage require specific treatment Hyperthermia Is an elevated body temperature due to failed thermoregulation that occurs when the body produces or absorbs more heat than dissipation. Hyperthermia differs from fever in the mechanism that causes the elevated body temperature. In all febrile neonates, a diligent search for a possible infective focus must be made. In summer months, hyperthermia may occur due to raised environmental temperature. This may be treated by moving the baby into cool environment and using loose light clothes for the baby. 102

13 Mild hyperthermia When the temperature is 37.5 C-39 C, undressing and exposing the neonate to room temperature is usually all that is necessary. Extreme hyperthermia When the temperature is above 38 C, the neonate should be undressed and sponged with tepid water at approximately 35 C until the temperature is below 38 C. Many times in nursery overheating under warmer is the cause rather than infection. 3.6 Neutral Thermal Environment (NTE) A neutral thermal environment is the environmental condition in which the temperature of the naked body does not change when the subject is at rest and there is no muscle activity. In a neutral thermal environment, the airflow, humidity, and temperature of surrounding radiating surfaces will minimize heat loss or gain through radiation, conduction, convection, and evaporation to keep the infant in a steady metabolic state. 1. NTE is the optimum environmental temperature to ensure the lowest oxygen and energy expenditure (Merenstein & Gardner, 2006) 2. The neonate may have to cope with either of two extremes THERMAL STRESS 3. Excessive HEAT LOSS or excessive HEAT GAIN, both of which are stressors. As the term and preterm neonate are incapable of thermoregulation, this presents a challenging career for the staff nurse who is charged with the responsibility of ensuring the neonate s temperature is maintained within a range conducive with life. The process of maintaining a constant body temperature for these neonates involves many processes and procedures [4]. Nurses need to pre-warm the incubator or radiant warmer before the infant arrives in the NICU. A warm incubator or warmer will help prevent conductive and radiative heat loss. It is essential for the nurse or other health care team members to ensure the neonate is kept at a constant and suitable environmental temperature, the neonate s core 103

14 body temperature is measured accurately and regularly, and that illnesses or factors that have the potential to impact on temperature regulation are managed. To enable the neonatal nurse to comprehend the complexities of thermoregulation in the neonate the nurse must be able to understand the anatomy and physiology of the neonate and the complexities that hyperthermia and hypothermia can cause in the preterm and term infant Neonatal Physiology 1. Neonatal physiology predisposes to poor thermal control 2. Wet skin at birth and high surface area to body ratio lost heat via skin surface. 3. Immature hypothalamus 4. Lack of subcutaneous fat (term) and/or adipose tissue or brown fat (preterm) 5. Poor energy stores and limited brown fat = limited thermogenesis (heat production). 3.7 Temperature Measurement and Thermoregulation in NICU Hypothermia is considered as a temperature >36.5 C, mild hypothermia is a temperature between 36 C 36.5 C, moderate hypothermia is classed as a temperature between 32 C - 36, and severe hypothermia <32 C. Hyperthermia will be classed as any temperature >37.5 C. Premature neonates have an immature thermoregulatory system; they need help with temperature control from the moment of birth, especially if <1kg. Some heat loss after delivery may be an important stimulus for metabolic adaption but it is important to avoid a continuous drop in body temperature proven to be detrimental to premature infants. If the baby is in an incubator, the air temperature should be lowered [5]. Hypothermia (temperature <36.5 C) is a common finding in premature infants following delivery, resuscitation and stabilization in the neonatal intensive care unit (NICU). During this period body temperature is highly dependent on the environmental temperature. Evaporative water losses in preterm infants are also a major problem during the first few minutes of life. Predisposing factors include a large surface area to mass 104

15 ratio, being wet at birth and skin immaturity. Evaporation, convection, conduction and radiation all play a role in the frequently rapid fall in body temperature. Conventional practice is to dry the newborn infant and place the infant under a radiant heater immediately after birth (McCall et al., 2010). Although this is an effective way of maintaining temperature in term infants, hypothermia remains a common problem in preterm infants. The method used to keep the baby warm will depend on the many factors, which can be taken care by various devices such as Infant Incubators and Radiant Warmers [6]. An incubator is an apparatus used to maintain environmental conditions suitable for a neonate (newborn baby). It is used in preterm births or for some ill full-term babies [7]. The radiant warmer is developed as an open incubator that ensures ready access to the baby. It provides intense source of radiant heat energy to maintain infants body temperature and prevents cold stress. To maintain the Axilla temperature of the baby in between 36.5oC to 37.2oC the infants are placed in incubator or radiant warmer. The Axilla (position shown in fig 3.6) temperature is measured even it is lower than the central temperature of the baby. It is easy to probe, neither affected by environmental changes nor interferes with X-ray fields, and not heated by heating device directly. Figure 3.6: Various parts on new born baby to measure Temperature 105

16 In an incubator the temperature of an infant is probed by the sensor. Now a day s many sensors such as thermocouples, thermistors, liquid thermometers and bimetallic strips are analog sensors available in market. 3.7 Hardware Development of the GSM Based Temperature measurement Thermoregulation of the system. The complete block diagram of GSM Based real time temperature measurement and thermoregulation of a preterm neonate is shown in figure 3.7, schematic diagram in figure 3.8 and in photograph 3.1. The system constructed and implemented with the following units. They are Figure 3.7: The block diagram of Temperature Measurement and Thermoregulation for the GSM Based Real time NICM System 106

17 Figure 3.8: The schematic diagram of Temperature Measurement and Thermoregulation for the GSM Based Real time NICM System 107

18 Photograph 3.1: The Schematic connections of Temperature measurement and Thermoregulation of a Premature neonate in NICU 1. Ceramic Heater 2. Temperature sensors (LM 35) 3. Signal conditioning Unit (RMS Voltage control Circuit) (i) Opto Diac (ii) Traic (iii) SPDT Relays (iv) Power supply 4. Raspberry PI Processor 5. GSM Module (SIM 500) 6. Mobile phone ( Samsung Duo) 7. Personal Computer A detailed explanation for each of them given as follows Ceramic Heater (1000Watts/230VAC) A heating element converts electricity into heat through the process of resistive or Joule heating. Electric current passing through the element encounters resistance, resulting in heating of the element. Unlike the Peltier Effect this process is independent of the direction of current flow 108

19 Ceramic heaters are space heaters that generate heat by passing electricity through heating wires embedded in ceramic plates. The plates heat aluminum baffles, and a fan blowing across the baffles heats the air. Ceramic heaters are usually portable and typically used for heating a room or small office, and are similar to metal-coil fan heaters. In the present study we used the ceramic heater of 1000 Watts/230 Volts AC from which the heat energy for thermo regulation required for preterm newborn infant having more advantages than the other heating sources such as heater coils, plates etc. The ceramic heater is shown in figure 3.9. Figure 3.9: ceramic heater element Temperature Sensors (LM 35) The Temperature Sensor LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 [8] thus has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1 4 C at room temperature and ±3 4 C over a full 55 to +150 C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35 s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies 109

20 Features of LM 35 temperature Sensor: 1. Calibrated directly in º Celsius (Centigrade) 2. Linear mv/ C scale factor C accuracy guarantee able (at +25 C) 4. Rated for full 55 to +150 C range 5. Operates from 4 to 30 volts 6. Less than 60 µa current drain 7. Low self-heating, 0.08 C in still air 8. Nonlinearity only ±1 4 C typical 9. Low impedance output, 0.1 Ω for 1 ma load Figure 3.10: LM35circuit diagram In the present work for the measurement of temperature and thermoregulation of a preterm neonate has been made using two temperature sensors of IC LM35 is as shown in figure One sensor is used for the neonate body temperature measurement and second sensor used for the measurement of air temperature. The two sensors outputs are connected to IC CA3140 voltage followers in the unity gain configuration and each sensor analog output is given to analog to digital converter PCF8591 which is serial ADC given to Raspberry PI processor. The two sensors will give secure safety measures to the neonate so that the temperature should not exceeds the set values of body temperature and air temperature values stored in the memory. If any one of these measurement exceeds the limits immediately a high pulse will send on port I/O line to control circuit to switch of the heater to maintain at constant temperature. The main purpose of using the serial ADC is to minimize the hardware and cost of the system. The 110

21 other details of signal conditioning of temperature measurement and thermoregulation with the help of opto-diac and Triac circuits are explained below Signal Conditioning Unit RMS Voltage circuit with Opto diac (MOC 3042) and Triac (BT 139) In any electronic measurement system consist of various units starting from sensors to data presentation units. Among that the signal conditioning unit is playing vital role to manipulate the input parameter of any sensor or transducer to the required form. Any system that may consists with Amplifiers, Filters, RMS converters, V-I, I-V converters, attenuators, ADC and DAC etc. In the present work for the temperature measurement and thermoregulation required for a preterm neonate we are using Opto- Diac, Triac, SPDT Relays and power source. The description of these is presented as follows Opto-isolator with Diac An opto-isolator is a solid state device designed to provide electrical isolation between input and output. The input consists of a light emitting diode (LED) in a six or eight pin dip (IC) package depending on type. The output can be a photo transistor, photo Diac, etc. There is no electrical contact between input and output. When the LED is turned on, the Diac, transistor, etc. will conduct from the light emitted from the diode thus turning on the triac like a switch. The MOC3011 series is made to connect to triacs, the MOC301x types for 110 volts, and the MOC302x types for 240 volts. In the present work the opto isolator with diac used is MOC3042 [9] and its connection details are given below figure Figure 3.11 : The pin and internal archtecture of Opto isolator 111

22 MOC3021 is an optodiac (product of Motorola) that is used for isolation between power and driving circuitry. Note that when C828 on the base is applied voltage>0.7v, optodiac gets triggered. As the diac gets triggered now, the positive or negative voltage (whatever maybe) get pass through the gate of BT139 (triac) and hence triggered it. It should be noted here that by using above arrangement we can control the RMS voltage in both directions. What needs to be taken care of, is the triggering time or firing angle. There is a need of a zero-crossing detector that will give us the reference for providing delay for desired firing angle. In above example, for firing angle to be 90' for 220V 50Hz AC signal, we need to have a delay of 2.5 ms (t1=2.5ms) right after each zero crossing. Usually MOC3021 is driven through microcontroller, which gives the firing pulse on the basis of interrupt generated by the zero-crossing detector Triac Triac is a power electronic component that conducts in both directions when triggered through gate. Figure below shows a generic working of triac with a snubber circuit. The Snubber circuits are used to prevent premature triggering caused for example by voltage spikes in the AC supply or those produced by inductive loads such as motors. Also, a gate resistor or capacitor (or both in parallel) may be connected between gate and Mt1 to further prevent false triggering. That could increase the required trigger current and perhaps a delay in turnoff as the capacitor discharges. In this circuit above the "hot" side of the line is switched and the load connected to the cold or ground side. The 39-ohm resistor and 0.01uF capacitor are for snubbing of the triac, and the 470 ohm resistor and 0.05 uf capacitor are for snubbing the coupler. These components may or may not be necessary depending upon the particular and load used. 112

23 Figure 3.12: The schematic digram of snubber with optodiac with Triac SPDT Relays with Triac Figure 3.13: the solid state relay The most basic solid state relay (SSR) is shown above figure 3.13 being a light source and a triac with a photosensitive gate. A solid state relay (SSR) consists of four main parts. We used four SPDT relays along with a resister network is arranged to reduce the heater wattage as shown in figure. The Raspberry PI GPIO lines of GPIO0, GPIO1, GPIO2, GPIO3 and GPIO4 are connected through base of the transistor to Relay1, Relay2, Relay 3 and Relay4 respectively. The out terminals of IC LM 35 are given to the Serial ADC inputs. The truth table of Ceramic heater control connected through Raspberry Pi processors GPIO lines are given below table 3.2. If the power failure automatically the relay that is connected GPIO4 will become high and switch on the burglar alarm to give indication to the system operators. 113

24 Table 3.2 : The truth heater power control Relay 3 Relay 2 Relay 1 Heater Power ( Watts) W W W The details of the temperature measurement and thermoregulation of the GSM Based NICU explained in the software development and its implementation Mobile Phone (Samsung Galaxy DUOS 18262) A mobile phone (also known as a cellular phone, cell phone, hand phone, or simply a phone) is a phone that can make and receive telephone calls over a radio link while moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile phone operator, allowing access to the public telephone network. By contrast, a cordless telephone is used only within the short range of a single, private base station. In addition to telephony, modern mobile phones also support a wide variety of other services such as text messaging, MMS, , Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming, and photography. Mobile phones that offer these and more general computing capabilities are referred to as Smartphone. Samsung Galaxy Duos is a dual SIM Smartphone, the phone also comes with Android Ice Cream Sandwich, along with Samsung's proprietary Touch wiz interface. Unlike entry-level dual SIM models from Samsung, the Galaxy S Duos is active on both SIMs all the time so it is ready to receive calls on either SIM when a call is not already in progress. Optionally it can receive two calls simultaneously but this requires divert-onbusy to be set up on each number and is subject to availability from the carrier and may incur additional charges. A limitation of the Galaxy S Duos is that only one SIM can be active on UMTS at a time and so it may be unsuitable for certain combinations of networks. 114

25 In the present work the Mobile phone containing SIM card has a specific number through which communication takes place. It communicates with the GSM Modem via radio frequency [25]. Mobile user transmits SMS using GSM technology. It is also used to monitor and control the status of the process parameters Raspberry PI Processor The output from signal conditioning unit is processed by using RASPBERRY Pi ARM11J6JZmicro controller. ARM[10] stands for Advanced RISC Machine. The ARM11 is based on the ARMv6 instruction set architecture. The block diagram of the internal architecture of the micro controller ARM11J6JZ is shown in figure The Raspberry Pi uses the Broadcom BCM2835 system on a chip (SoC) [11]. The Raspberry Pi model B has 512MB of primary memory (RAM). Clock speed is 700MHz. The Broadcom BCM2835 is the specific implementation of an ARM11 processor. The CPU core is the ARM11J6JZFwhich is a member of the ARM11 family (ARMv6 architecture with floating point). The GPU is a Videocore IV GPU. This is mainly consists of the following units embedded inside the chip. The important features of the ARM11J6JZcore is of the following Eight stage pipeline Internal coprocessors CP14 and CP15 Three instructions sets 32-bit ARM instruction set (ARM state) 16-bit Thumb instruction set (Thumb state) 8-bit Java bytecodes (Jazelle state) Data path consist of three pipelines: ALU, Shift, Sat pipeline (Sat implements saturation logic) MAC pipeline (MAC executes multiply and multiply-accumulate operations) Load or store pipeline The ARM Memory Management Unit (MMU) translates virtual addresses to physical addresses using page information. The MMU supports four page sizes: 4KB small pages, 64KB large pages, 1MB sections and 16MB super sections. Address mapping is performed using two levels of translation look aside buffers: the Main TLB 115

26 and two micro TLBs. The Main TLB backs separate micro TLBs for each of the instruction and data caches. Address translation is first attempted in a MicroTLB. If the address cannot be translated in the MicroTLB, then the Main TLB is tried. If the address cannot be translated through the Main TLB, then hardware page walking is invoked. Figure 3.14: Blocks Diagram of the ARM11J6JZF The circuit diagram of interfacing temperature sensors circuit, memory...etc to a micro controller is as shown in figure 3.8. In the present design ARM11J6JZis the central processing unit do the total processing. The micro controller is connected to all external devices like ceramic heater, amplifier, ADC, USB, Graphical LCD. Every external device has their own input/ output lines. The sensor output is connected to the GPIO pins of the micro controller. LCD communicates serially with the micro controller. 5 lines are used to interface with the micro controller. Universal Serial Bus uses Differential lines to communicate between micro controller and Personal Computer. The system having memory interface with an external memory up to 16GB where the system software as well as the application software developed can be stored to execute the operations as small CPU without personal computer. The interfacing connection details of temperature measurement and thermoregulation already presented. The RaspnerryPi Central Processing Unit and its connections is as shown in Photograph

27 Photograph 3.2: The RaspnerryPi Central Processing Unit and its connections GRAPHICAL LCD DISPLAY (TOUCH SCREEN - AT070TN92 The output of the device is sent to a liquid crystal display to display the temperature of the baby. In present design we are using GRAPHICAL LCD DISPLAY TOUCH SCREEN - AT070TN92 [12]. The pin description and the specification of AT070TN92 are as shown in table 3.3. AT070TN92 is 800x480 dots 7" color TFT LCD module display with OTA7001A controller, optional 5 points capacitive multi-touch panel with connector and 4-wire resistive touch panel screen with connector. A thin-filmtransistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display (LCD) that uses thin-film transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active-matrix LCD, in contrast to passivematrix LCDs or simple, direct-driven LCDs with a few segments. It has superior display quality, super wide view angle and easily controlled by MCU ARM. It can be used in any embedded systems, car, mp4, gps, industrial device, security and hand-held equipment which require display in high quality and colorful image. It supports RGB interface. FPC with zif connector is easily to assemble or remove. 117

28 Table 3.3: The pin description of AT070TN92 Peninterrupt If the user does not touch the screen for a long period of time, there is no need for operation or measurement. The touch screen is then put in sleep mode and waits for a pen interrupt. Upon user touch, an interrupt occurs and the touch screen controller wakes up and measures touch parameters. The port pin that is connected to touch screen XP connector is configured to pullup mode and set to a logic state of high. The port pin connected to the XM connector is configured as a digital input and the interrupt is enabled by falling edge. If the lower screen is still untouched, XM holds the logic in high states. If the user touches the screen, the voltage of XM falls to a low logic level and initiates an interrupt that wakes up the PSoC. Graphical LCD display interface photograph is as shown in fig

29 Photograph 3.3 : Graphical LCD display interface circuit GSM MODEM - SIM500 The Global System [13] for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. A GSM modem is a specialized type of modem which accepts a SIM card, and operates over a subscription to a mobile operator, just like a mobile phone. From the mobile operator perspective, a GSM modem looks just like a mobile phone. A GSM modem can be a dedicated modem device with a serial, USB or Bluetooth connection, or it may be a mobile phone that provides GSM modem capabilities. The term GSM modem is used as a generic term to refer to any modem that supports one or more of the protocols in the GSM evolutionary family, including the 2.5G technologies GPRS and EDGE, as well as the 3G technologies WCDMA, UMTS, HSDPA and HSUPA. GSM module is the kernel part to realize wireless data transmission. Wireless communication module SIM500 based on standard of GSM produced by SIMCOM company is used in the developed application. SIM500 module consists of main frame, antenna, serial communication line, power line. It provides services of wireless modem, wireless fax, short message and speech communication. The short message service is suitable to apply in the situation of frequent transmittance of small data flow. 119

30 SIM500 is a Tri-band GSM/GPRS engine that works on frequencies EGSM 900 MHz, DCS 1800 MHz and PCS1900 MHz. With a tiny configuration of 40mm x 33mm x 2.85 mm, SIM500 can fit almost all the space requirement in your application, such as Smart phone, PDA phone and other mobile device. The physical interface to the mobile application is made through a 60 pins board-to-board connector, which provides all hardware interfaces between the module and customers boards except the RF antenna interface. The keypad and SPI LCD interface will give you the flexibility to develop customized applications. Two serial ports can help you easily develop your applications. Two audio channels include two microphones inputs and two speaker outputs. This can be easily configured by AT command. SIM500 provide RF antenna interface with two alternatives: antenna connector and antenna pad. The antenna connector is MURATA MM And customer s antenna can be soldered to the antenna pad. The circuit of SIM500 is shown in photograph 3.4. Photogrpah 3.4 : SIM500 Circuit The SIM500 is designed with power saving technique, the current consumption to as low as 2.5mA in SLEEP mode. The SIM500 is integrated with the TCP/IP protocol, Extended TCP/IP AT commands are developed for customers to use the TCP/IP protocol easily, which is very useful for those data transfer applications. The leading features of SIM 300 make it ideal for virtually unlimited applications, handheld devices and much more. It is compatible with AT cellular command interface. 120

31 The features of SIM500 are Tri-Band GSM/GPRS 900/1800/1900 MHZ Complaint to GSM phase 2/2+ Dimensions: 40mm x 33mm x 2.85mm Weight : 8g Control via AT commands SIM application tool kit Supply voltage range v Low power consumption All hardware interfaces except RF interface that connects SIM500 to the customers cellular application platform is through a 60-pin 0.5mm pitch board-to-board connector. Sub-interfaces included in this board-to-board connector are Dua,l serial interface,two analog audio interfaces, SIM interface SIM500 provides two unbalanced asynchronous serial ports. The GSM module [14] is designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data Terminal Equipment) connection, the module and the client (DTE) are connected through the following signal as shown in figure Auto bauding supports baud rate from 1200 bps to bps. Serial port 1 Client sends data to the RXD signal line of module Client receives data from the TXD signal line of module Serial port 2 Client sends data to the DGBRXD signal line of module Client receives data from the DGBTXD signal line of module Figure 3.15 : Interface of serial ports 121

32 The TXD, RXD, DBG_TXD, DBG_RXD, GND must be connected to the IO connector when user need to upgrade software and debug software, the TXD, RXD should be used for software upgrade and the DBG_TXD, DBG_RXD for software debug. The PWRKEY pin is recommended to connect to the IO connector. The user also can add a switch between the PWRKEY and the GND. The PWRKEY should be connected to the GND when SIM500 is upgrading software. The SIM interface supports the functionality of the GSM Phase 1 specification and also supports the functionality of the new GSM Phase 2+ specification for FAST 64 kbps SIM. Both 1.8V and 3.0V SIM Cards are supported. The SIM interface is powered from an internal regulator in the module having nominal voltage 2.8V. All pins reset as outputs driving low. The Figure 3.16 is the reference circuit about SIM interface. The 22Ω resistors showed in the figure should be added in series on the IO line between the module and the SIM card for matching the impedance. The pull up resistor (about 10KΩ) must be added on the SIM_I/O line. The SIM_PRESENCE pin is used for detecting the SIM card removal. We can use the AT command AT+CSDT to set the SIMCARD configure. We can select the 8 pins SIM card. Figure 3.16: SIM interface reference circuit with 8 pins SIM card The GSM AT commands are for performing SMS and CBS related operations. The Overview of AT Commands According to GSM07 [29] is listed in Table

33 Table: 3.4. Overview of AT Commands According to GSM Software development The processing unit utilizes the logic implemented in the software for accurate measurement and control of temperature of a Newborn infant in NICU. The software checks the input signal from the Temperature sensors one is attached to the neonate for the measurement of body temperature and second one is for air temperature. It continuously measures the neonate s body and air temperature and compares these values with the internal set value. If there is any change in these the raspberry pi switches on or off as per the logic developed in the program. In the present study the c language used for the development of software having the following features. The C programming language is growing in importance and has become the standard high-level language for real-time embedded applications. PC is the standard for computing the concept of a C compiler [15]. To development of C programs for an Mcrocontroller executing on a PC is now familiar with IAR Embedded IDE only. This largely due to the inherent language flexibility, the extent of support and its potential for portability across a wide range of hardware [16]. Specific reasons for its use include It is a midlevel with high level features and low-level features It is very efficient, it is popular and well understood Good well-proven compilers are available for every embedded processor these 123

34 Books, training courses, code samples and world wide web sites discussing the use of the language are all widely available EMBEDDED Based LINUX - QT Programming In the present work the software development for the development of Blood pressure meter was developed using the software of embedded linux and its GUI design developed is QT. Linux itself is a kernel, but Linux in day to day terms rarely means so. Embedded Linux generally refers to a complete Linux distribution targeted at embedded devices. There is no Linux kernel specifically targeted at embedded devices, the same Linux kernel source code can be built for a wide range of devices, workstations, embedded systems, and desktops though it allows the configuration of a variety of optional features in the kernel itself. In the embedded development context, there can be an embedded Linux system which uses the Linux kernel and other software or an embedded Linux distribution which is a pre-packaged set of applications meant for embedded systems and is accompanied by development tools to build the system. The Qt framework first became publicly available in May It was initially developed by Harvard Nord (Troll tech's CEO) and Eirik Chambe-Eng (Trolltech's Chief Troll). Qt has long been available to non-c++ programmers through the availability of unofficial language bindings, in particular Py.Qt for Python programmers. In 2007, the Qyoto unofficial bindings were released for C# programmers. In 2007, Troll tech launched Qt Jambi, an officially supported Java version of the Qt API. Since Troll tech's birth, Qt's popularity has grown unabated and continues to grow to this day. This success is a reflection both of the quality of Qt and of how enjoyable it is to use. In the past decade, Qt has gone from being a product used by a select few "inthe know" to one that is used daily by thousands of customers and tens of thousands of open source developers all around the World. The signals and slots mechanism is fundamental to Qt programming. It enables the application programmer to bind objects together without the objects knowing anything about each other. We have already connected some signals and slots together, 124

35 declared our own signals and slots, implemented our own slots, and emitted our own signals. Let's take a moment to look at the mechanism more closely. Slots are almost identical to ordinary C++ member functions. They can be virtual; they can be overloaded; they can be public, protected, or private; they can be directly invoked like any other C++ member functions; and their parameters can be of any types. The difference is that a slot can also be connected to a signal, in which case it is automatically called each time the signal is emitted. Qt provides a complete set of built-in widgets and common dialogs that cater to most situations. we present screenshots of almost all of them. A few specialized widgets are deferred. Main window widgets such as Q MenuBar, Q ToolBar and Q StatusBar and layout-related widgets such asq Splitter and Q ScrollArea. A widget is a user interface component such as a button or a scroll-bar are Reusable, Well defined interface,uses C++ inheritance, All widgets derive from a common base, Widgets may contain other widgets, Custom widgets can be created from existing widgets or they can be created from scratch. The Qt designer window is as shown in figure 3.18 QT DESIGNER Written using Qt so it is available on all platforms where Qt is available Used to speed design of Qt applications Supports all Qt widgets and can be used to incorporate custom widgets Figure 3.18 : QT designer window 125

36 FEATURES Fully object-oriented Consistent interfaces Rich set of widgets (controls) Have native look and feel Drag and drop Customizable appearance Utility classes OpenGL support Network support Database support Plugin support Unicode/Internationalization support GUI builder Based on the above advantages, we used the Qt software for the present work. The algorithm and flow chart of the touch screen based electronic voting machine as shown below. After creation of project and the program, we executed the program. Then executed program is downloaded in to the micro controller. The download program is executed in micro controller with external hardware interface then we can get the results. If we get wrong results then modify the program and do the same process as above till to get the correct results. Software program for Temperature measurement is presented in Annexure I 126

37 3.8.1.Algorithm 1. Initialize central processing unit Raspberry Pi 2. Initialize Ports, Graphical LCD, DAC 3. Initialize Relays to default position 4. Measure Temperature using LM35 and transfer data to microcontroller through ADC 5. Check the temperature, if it is normal set relays in normal position 6. otherwise change control of other relay to switch on/off 7. If the temperature is out of range switch on the Buzzer 8.Display the measured temperature on Graphical LCD Display 9.Repeat the process from step 4 127

38 Flowchart Figure 3.19 flow chart for Temparature Measurement and Thermoregulation 3.9. Temparature Measurement and Thermoregulation of GSMNICS The designed hardware of the system interfaced with Raspberry PI processor implemented by executing the software developed for health monitoring of a premature neonate in Intensive care unit. When the program is executed which is stored in Sony MicroSD card 8GB, a window designed for the present work will be displayed on the Touch screen Graphical LCD Display as shown in photograph 3.5 with the following buttons. They are 128

39 1. Temperature 2. Phototherapy 3. SPO2 4. NIBP 5. Total system and 6. Exit Photograph 3.5: Main window of GSM based Real Time Neonatal Intensive care monitoring system The implementation of the measurement and control process of the GSM based Real Time Neonatal Intensive care Monitoring system presented with the windows as follows. If in the above main menu Total System is selected then the total health parameters of Temperature, Phototherapy, SPO2 and NIBP measurement values are displayed individually as in the program the total display divided into four screens and each screen is allotted for the measured parameters to be displayed with two control buttons of close and Send SMS. Total System Health parameter measurement window is as shown in Photograph

40 Photograph 3.6 : Total System Health parameter display measurement window In the present work of the temperature measurement and Thermoregulation of a preterm neonoate of ICU, When the Temperaturetton is selected then a real time GUI will be displayed developed for monitoring and control of temperature with all control buttons as shown in photograph 3.7 consists of the following. They are Photograph 3.7 : Temperature measurement and Thermoregulation window display 1. Set Temperature 2. Baby Temperature 130

41 3. Air Temperature 4. Heater value 5. Set Timer count and 6. Set Timer selection 7. Reset 8. Stop The detailed explanation for each button in the GUI is given as follows. Set Temperature The function of this button is to set the temperature measurement and control for a particular value. Which will be stored in the memory of the Raspberry Pi board. Baby Temperature The function of this button is to measure the Baby temperature measurement and compared with the set temperature to switch ON/OFF of the Ceramic Heater which will be provide safe and secure measures to the neonate. Air Temperature The function of this button is to measure the Air temperature measurement and compared with the set temperature to switch ON/OFF of the Ceramic Heater which will be provides safe and secure measures to the neonate. Heater value The function of this button is used to select the wattage of the ceramic heater by selecting 50, 75 and 100% by selection of SPDT Relays with resistor network and Port I/O s of Raspberry Pi to control the radiation of the heater. Set Timer count The function of this button is used to select the duration of the required time for thermoregulation of the neonate as per the advice of the Doctor and after the count is over it is automatically switch off the heater. 131

42 Set Timer selection The function of this button is used to select the duration of time in hours, minutes and seconds as per the advice of the doctor and same will be worked as Real time when the thermoregulation process is in progress. Reset The function of this button is used to reset all the previous values to normal values and will be used for the next neonate to admit into NICU. Stop The function of this button is used to stop all the process temporarily If any one of the set values of either Baby temperature or the air temperature exceeds then immediately a SMS through GSM Modem will send the current temperature values and heater position to the concerned Nurses/Doctors Mobile Phones as shown in Photograph 3.8. Photograph 3.8: Measured Health Parameters in Mobile Phones 132

43 Photograph 3.9 : Temperature measurement and Thermoregulation GSM based Real Time Neonate Intensive Care System Results & discussions. The aim and objective of the present work as a part of GSMNICS to design and implementation of Temperature measurement and Thermoregulation of a neonate in NICU with real time touch screen based GUI display which provides all information and easy operation. It also communicating the data or information that is measured and controlled or transmitted to the concerned person s mobile phones through SMS by advanced technology of GSM. The device doesn t restrict the movement of the patient. The system is easily expandable paving the way to incorporate much more health parameters with sophisticated designed devices in the future course. the system is implemented successfully with the measurement accuracy of o C and the system tested values are presented in the table 3.5 Table 3.5 : Measured Temperature values S. No Set Baby Air Heater SMS message Temperature Temperature Temperature Condition ºC 29ºC 29ºC 36.9ºC 36.9ºC 36.9ºC 30ºC 29ºC 26ºC OFF OFF ON Crossing Limit Below the Limit No Message 133