Low-Cost Wireless Sensor Networks for Building Applications Using Novel Materials and Energy-Efficient Communications Scheme Teja Kuruganti Ph.D. Email: kurugantipv@ornl.gov Phone: 865-241-2874 Pooran Joshi, Stephen Killough, Edward Vineyard, Patrick Hughes Oak Ridge National Laboratory Oak Ridge TN, 37831
Leverage Unique Capabilities to Impact Energy Use Problem Statement Buildings consume up to 40% of energy produced in the US. Do we have a solution? Technology Solution Advanced sensors and controls have the potential to reduce energy consumption of the buildings by more than 20%. Our Participation ORNL has unique capabilities to deploy new class of sensors Source: http://www.idsc.ethz.ch Buildings (EERE Goal) Improve building energy efficiency 50 percent, in a cost- effecbve manner, by 2030. 2 Managed by UT-Battelle
Flexible and Printed Electronic Technology Material InnovaBons to Manufacturing Technology Advanced Devices ORNL s R&D PlaSorm Bio-Sensor Materials PrinBng Technology Device IntegraBon Test & Measurements Solar Cell To Impact Technology and Play a Lead Role Ø Advanced Materials R&D Ø Key Solu7ons and Core IPs Ø Integrated Prototypes Ø Technology Vision for Cost/ Performance Barrier Ø Manufacturability Building Block Plastic Integrated Thin Films - Metal - Semiconductor - Dielectric Market PotenBal US $44.25 Billion Market by 2021 - IDTechEx 3 Managed by UT-Battelle
Requirements for Building Monitoring Non-Orthogonal Multi-dimensional requirements for low-cost wireless sensors Application Requirements (data rate, sensor accuracy, sampling rate, battery, RF communications) Integration Requirement (printable materials, functionality, device/sensor integration, regulations) Cost: Low-cost, Manufacturing infrastructure (COTS wireless sensors are still at a high cost per node) ASHRAE Standards 90.1, 90.2, 55, 62.1, and 189.1 IECC, IBC, and NFPA 5000 code. 4 Managed by UT-Battelle Impact on Buildings Technology Advanced Sensor, Control Technology Brings Big Growth to Building Energy Management Market: Market Growth: 17% compound annual rate to become a $2.14 billion industry by 2020(Lux Research) Self-powered, Wireless Technology will Enable Multifunctional Sensor Platform at feasible cost and reliability Integration Cost
Low-Cost, Multi-Sensor Wireless Platform R&D Core Components High performance thin films Low temperature integration R2R processing setup Infrastructure investment already made Financial support and resources required for timely development R&D Extensive Capabilities at ORNL Modeling Design Test and Measurements Market Potential: Not just an improvement over existing technology Prospects of New market, Enhanced Functionality Energy Management Technologies Extensive know-how at ORNL Resources required to target low temperature material/device development 5 Managed by UT-Battelle
Additive Integration Approaches CMOS Processing Demands on Material Performance do not change significantly Substrate Integra7on Si: CMOS T<1000 C Glass: Transparent Electronics T<600 C Plastic: Low-cost Electronics T<200 C 3D Structures: Free- form http://www.plasticsto Resolu7on: 0.02µm Resolu7on: 10µm Resolu7on: 50µm 6 Managed by UT-Battelle Integra7on Opportunity: Mask- less Design
Printed Conductors Printing Challenges: Resolution Process tolerance Defect density Printing yield Metal Integration on Plastic Substrates Printable Conductor Level 1: R sh < 200 Ohms/Sq. Level 2: R sh < 20 Ohms/Sq. Line Width/Spacing Control Available Technology: 10-20µm Advances in Metal Ink Technology Metal Bulk Conductivity (µω-cm) Nanoparticle Ink Conductivity (µω-cm) Ag 1.6 2 Cu 1.7 5 Al 2.8 5 Ni 7.0 20 Our Focus: Establish plastic compatible photonic curing: Unique ORNL Setup Establish critical know-how: Plastic/Metal interface Evaluate Ink Technology: Performance of Key Metals of Interest 7 Managed by UT-Battelle Energy Harvesting
Printable Antenna Printable, flexible patch antennas for operation in ISM frequency bands (2.45GHz, 900MHz, and 433MHz) Printable dielectric materials and metals for optimal radiation pattern for producing thin-profile conformal antenna Use of pulse thermal processing for low temperature curing, printable polymer dielectrics for high performance, and antenna radiation pattern control Antenna characterization in RF clean room to achieve 2-3dBi gain in 2.45GHz range S21 parameter measurement 8 Managed by UT-Battelle S11 parameter measurement
Printed Circuit and Antenna on Paper Printed Monopole Antenna on Flexible Substrate (a) (b) Antenna Design: 2.45 GHz Printed High Frequency Monopole Antenna Return loss below -10dB easily achieved Addressing demands for small size, ease of fabrication, tunability, and low cost for shortrange applications. 9 Managed by UT-Battelle
Resonator Development for Stable Clock Source Printable stable clock source for integrated wireless sensor Printing metal on plastic, material selection for stable frequency High quality resonant transmission line stub or surface acoustic wave device using printable metal techniques and spread spectrum techniques for controlling frequency deviation Resonator characterization for undesired frequency shifts due to construction tolerance, temperature, and conformal shape Resonant Frequency Stability: ISM Band Operation 0.20 Temperature Stability of Resonator Frquency 0.15 Stub Resonator Performance Frequency Shift (%) 0.10 0.05 0.00-0.05-0.10-0.15 10 Managed by UT-Battelle - 0.20-30 - 20-10 0 10 20 30 40 50 60 70 T ( C)
Thin Film Temperature and Relative Humidity Sensor Development Inkjet Printing of Ag 1 Jetting Waveform 2 3 Printed Metal Performance 2.5 2.0 Flexible Sensor Inkjet Printed Strain Gage: Gage Factor Level:100% 3.456µs (ΔR/R) % 1.5 1.0 Slew Rate: 2.00 0.5 Level:0% 1 Fluid chamber at maximum volume 2 Main drop ejection phase 3 Recovery phase Line width control below 100µm established (Path towards 25µm) Circuit on Paper GF for metallic foils are typically between 2-5. 0.0 0.0 0.2 0.4 0.6 0.8 1.0 ε (%) Mechanical Integrity: Gauge Factor comparable to Metallic Foils Resistance (Ω) 10 8 6 4 2 Inkjet Printing: Ag/PI (Annealing Time 15minutes) Approaching Bulk Conductivity R Rsh 2.0 1.5 1.0 0.5 Rsh (Ω/Sq.) Additive Integration on Paper, Plastic, Ceramic, and Rubber 11 Managed by UT-Battelle IDE on Plastic 0 0.0 50 100 150 200 250 300 350 Annealing Temperature ( C) Printed Metal Conductivity approaches the Bulk value
Thin Film Temperature and Relative Humidity Sensor Development Humidity sensor with a resolution of ±2% RH Capacitance (pf) 250 225 200 175 150 RH Sensor Integration on 5-125µm thick PI films Mesh Electrode: Additive Integration eliminates masking, photo, and etch steps High Performance matching RH commercial sensors 12 Managed by UT-Battelle Inkjet Printed Capacitive RH Sensor Printed Capacitive RH Sensor Sensitivity: 0.50pF/%RH 40 50 60 70 80 90 100 Relative Humidity (%) (a) Performance matching commercial Honeywell Sensor Low-cost, low temperature metal thin film temperature sensor Resistance (Ω) 200 175 150 125 100 75 50 25 0 Inkjet Printed Resistive Temperature Sensor Printed Temperature Sensor 0 10 20 30 40 50 60 70 80 90 100 Temperature ( C) Sensitivity: 1.02 10-3 / C Temperature Sensor Linear Thermal Response from Printed Temperature Sensor Resistance can be controlled by Line Definition control: No mask redesign step (b)
Signal Processing Software-based measurement of the capacitance or the resistance for the various sensors RC time constant calculation routine similar to a 555 timer circuit Measure the capacitance if resistor value is known, or conversely the resistance can be measured if the capacitance is known. Capacitance measurement for humidity and eventually other chemical sensors General purpose Analog to Digital converter available on computer B+ Decoder Computer Comparator Threshold Reset 1 RC 13 Managed by UT-Battelle
Energy Harvesting 5 Voltage profile 4.5 Disharge Charge 4 Substrate: UV ozone treatment (20min) PEDOT:PSS (30-35nm)/ITO (Spin coating 4000rpm) Active layer: PTB7:PC 71 BM (1:1.5) in o- dichlorobenzene (concentration 25 mg/ml) (Spincoated on PEDOT:PSS film) Bottom Contact: Al/Ca (Thermal Evaporation) Voltage (V) 3.5 3 2.5 2 0 2 4 6 8 10 12 Capacity (mah) Current Density (ma/cm 2 ) 20 15 10 5 J SC = 14.1 ma/cm2 V OC = 0.7 V FF = 64% PCE = 6.3% The pouch cell offers a simple, flexible and lightweight solution to battery design. The pouch cell achieves a 90 to 95 percent packaging efficiency: Highest among battery packs 0 0.4 0.2 0.0-0.2-0.4-0.6-0.8-1.0 Voltage (V) 14 Managed by UT-Battelle Device Performance Efficiency (η) 6.3% Fill Factor (FF) 64% Short Circuit Current Density (J sc ) 14.1 ma/cm 2 Open Circuit Voltage (V oc ) 0.7 V
Power Harvester Voltage Measurement Transmit Voltage Charging from PV (~ 80 sec) Seconds Data for ~ 1.5 Sec of operation 15 Managed by UT-Battelle
Energy Efficient Communication Scheme Transmi[er Frequency Transmi[er Power Receiver Sensi7vity Chipping Rate Data rate Calculated Free Space Range 433.92 MHz +5 dbm - 145 dbm 2000 BPS 40 BPS 88 miles Using Data to preload the shift registers Generates different Gold codes and shifts the starting point of the code Most any radio could get much longer ranges at 40 BPS but Radio frequency tolerance for 40 Hz bandwidth is very tight and thus expensive Radio frequency tolerance for 2000 Hz bandwidth is reasonable and thus moderate in cost CDMA techniques can allow simultaneous usage to recover most of the expanded bandwidth 16 Managed by UT-Battelle
Integrated Sensor System The current performance specs are: Reporting rate: a transmission every 80 seconds Light required: office lights (fluorescent lamps) Parameters measured: Temperature, humidity, light intensity 17 Managed by UT-Battelle 17
Multifunctional Sensor Platform: Technology Impact Areas Focus: Advanced Sensors Metal, Semiconductor, Dielectric Printing Explore in-house Developed Technologies Focus: Pulse thermal processing for Plastic/Paper integration TFT Integration Nanomaterials Technology Focus: Energy Harvesting Develop Flexible Solar Cell and Thin Film Battery Co-integrate Energy Harvesting Components Focus: Advanced Flexible Circuits Printed Antenna and Driving Circuit Co-integration Multiple, Multifunctional Components for Advanced Sensor Platform 18 Managed by UT-Battelle
Conclusions and Future Work Designed and demonstrated initial prototype lowcost wireless sensor for building applications Printable sensors and PV Metal-on-plastic printing of circuit pattern Prototypic demonstration of sensors and PV on plastic Advanced gas sensors using novel nano-materials Improved network stack design for energy efficient network of nodes Integration of printable battery storage 19 Managed by UT-Battelle