Micro-Power Systems for Ambient Intelligence

Micro-Power Systems for Ambient Intelligence Cian O Mathuna Terence O Donnell, Saibal Roy, Brendan O Flynn, James Rohan Tyndall National Institute, Cork, Ireland omathuna@tyndall.ie +353 21 4904350

Presentation Overview Application requirements for Ambient Systems Environmental monitoring "On the body" monitoring Power System Components Energy Harvesting: vibration harvesting and scaling human motion harvesting Storage: Fuel cells and batteries. Power Conversion Power supply on chip Conclusions

End-User Applications Enabled by External Collaborations Healthcare Point-of-Care Diagnostics Electro-genetherapy Neural Stimulation Smart Pill Environment Remote Environment Management Building Energy Management Sustainable Agriculture

Research Theme: Wireless Sensor Systems Research Focus: Hardware and Software Technology Platforms for Autonomous Wireless Systems Miniaturised Autonomous Wireless Microsensor Modules Distributed, Ad-hoc Wireless Sensor Networks Deployment in End-User Applications Hardware Features: Modular, Flexible, Reconfigurable, Scaleable, Robust Sensors Drivers / Controllers Data Processing Communications Power Tyndall 25mm Mote - Under Evaluation by >20 Research Teams in Ireland, Europe, USA.

Research Theme: System Integration and Packaging Research Focus: Technologies for miniaturisation of wireless sensor modules. 25mm Cube to Sugar Cube to Intelligent Seed 25mm 10mm 5mm

Research Theme: Micropower for ICT Research Focus: Technologies for micropower generation/transmission, storage and conversion. Energy Source - Vibration Harvesting - Solar Cells - Piezoelectrics - Inductive Power - Microfuel cells Energy Storage - Microbatteries Power Conversion - Power Supply on Chip - Magnetics on Silicon

Around the Body : Environment Sensor Interfacing: Temperature PH Conductivity Dissolved Oxygen Node Battery Microcontroller RF Transceiver Sensors Gateway Node Wireless Systems Hardware Software Standards Ruggedisation & System Integration

On the Body : Wearable Technology Human Computer Interface Sign language interface to computer via inertial sensor module Physiotherapy Mobile Phone / SMS / GPS Elderly Care Personal Security Accelerometers + Gyroscopes XSENS MT9 Inertial Measurement Unit (IMU) located in heel cavity

In the Body : Smart Systems for Digital Health Diagnostic implant Personal AdvisoryWatch Endoscopic Analysis Capsule Implant coil for nerve stimulation Intervention implant Improve quality of life for long term ill people Early stage disease intervention Keep the patient out of hospital Flexible Electrode devices for retinal stimulation

Sensor Selection For Application Area Environmental Large (rugged) High Power consumption (microfluidic pumps etc) DO Sensing, 300 mw Temperature & Turbidity Sensing ~450 mw, PH Sensing, ~ 200 mw, Conductivity Sensing ~150mW Wearable Small/Light Low power consumption Inertial Sensing, Tyndall IMU - Temperature Sensing Proximity Sensing

Power System for wireless sensors Software: e.g Low Power Protocols Power supply on chip Energy Management Energy Source Source Conversion Storage Load conversion Solar Vibrations Movement Thermal Micro-batteries Micro fuel cell Capacitors Loads: Sensors Data processor RF transceiver

Power Budgets P (W) Energy Consumption peak power Energy Consumed must equal energy available on off standby/sleep time (s) 86400s (24h) Ideally we want our device doing nothing 99.999% of the time

Energy Harvesting: Solar 30000 lux (outdoor cloudy) 450 lux (indoor) Iowa (A-Si) Iowa (A-Si) Solems (A-Si) Solems (A-Si) RWE Solar (A-Si) BP Solar (P-Si) Iowa (A-Si) Iowa (A-Si) Solems (A-Si) Solems (A-Si) RWE Solar (A-Si) BP Solar (P-Si) 0 1 2 3 4 5 max power output mw/cm2 0.0 5.0 10.0 15.0 Max power output uw/cm2 Measurements on commercially available solar cells indoor and outdoor (Ireland)

Energy from Vibration Electromagnetic vibration energy harvesting device Silicon beam Housing Copper coil Magnets Tungsten mass Devices built in University of Southampton, and modelled by Tyndall Latest optimised version provides 50 microwatts @ 350 mv from 0.06g at 100 Hz

SOA: Vibration Generators 100 Normalised (to 0.5 m/s 2 ) Power density of vibrational generators vs. the generator volume VIBES EM Generator Power Density (nw/mm 3 ) 10 1 0.1 0.01 Only fully micro-fabricated Piezo-electric Generators Electromagnetic Generators Electrostatic Generators 0.001 0.1 1 10 100 1000 10000 100000 1000000 Volume (mm 3 )

Theoretical predictions EM Generators Power (W) 1.00E+00 1.00E-01 1.00E-02 1.00E-03 Maximum Electrical Power Load Power: Wire-wound coil Load Power: Micro-Coil Qoc = 20,000 Theoretical maximum power (1 g, 1 khz) If we could achieve high mechanical Q-factor With actual measured mechanical Q-factor 1.00E-04 Qoc = 300 1.00E-05 1.00E-06 0 2 4 6 8 10 Dimension (mm)

Energy Harvesting from Human Motion Magnet fixed on top end of the tube N S 2 Movable middle magnets fasten in small t ube S 1 Coil Generator housing/tube Magnet fixed on bottom end of the tube N N S S N Acceleration (g) 0 0 0.5 1 1.5 2-1 Acceleration-rucksack walk Acceleration-rucksack slow run -2 Time (s) Generator tube dimension (mm) : 20 x 60 Average measured load power Walking : 0.13 mw Slow running : 0.54 mw Generated Voltage (V) 7.5 5 2.5 0-2.5 Voltage-rucksack slow run Power-rucksack slow run 0 0.5 1 1.5 2 8.75 7 5.25 3.5 1.75 Load power (mw) -5 0 Time (s)

CR2025 coin cell 160mAhr LPP402025 Varta Li-ion 140mAhr Performance comparisons Micropower source Micro battery Micro battery Micro fuel cell Micro fuel cell Micr fuel c Couple Li/LiCoO NiOOH/Zn Methanol/air H 2 from BH 4- /air H 2 from B Minimum cell size cm 2 50 x 50 μm 0.1 1.625 0.8 6 Active material Power Density Charge storage capacity Discharge current Issues μm 4 100 evap thin film on DRIE silicon thin film on Al 2 O 3 disper catalyst continuous mw/cm 2 1 75+ 16 (at RT) 3 40 peak mw/cm 2 30 140 50 (at 60 o C) 20 (10ms) mahr/cm 2 0.1 1 91 ma/cm 2 0.2 100 ~100 (at RT) 6 to 40 >100 Current drain low high high high high Capacity low low high high high Hybrid for for recharge recharge no no no Self probable minimal discharge issue minimal minimal minim Cost moderate moderate high moderate moder Membrane solid no yes no yes

Microbatteries Typical lithium based microbattery 1000 s cycles but current drain in μa and low capacity Company / Institute Tel Aviv University Brigham Young University Technology Issues Si DRIE Aqueous Zn Ni Si DRIE in each battery. Thin layer electrodes and electrolyte deposition in 3D Planar arrangement Ni-Zn lower energy density than Li systems Issues ORNL image Solid electrolyte Low conductivity Thin film protective coating Prevent lithium loss (capacity loss) by oxidation UCLA UCLA Naval research Lab Wash. DC Sediment electrode materials DRIE Si Lithium utilising carbons in Lithium nanoscale with nanoscale electrolytes in development Si DRIE mould formation. No integration of other elements SU8 pillars to be pyrolysed - high temp Integration of other battery elements Full cell assembly with nanoscale componentsn

Micropower sources at Tyndall EU FP6 IP Napolyde www.napolyde.org NANO-STRUCTURED POLYMER DEPOSITION PROCESSES FOR MASS PRODUCTION OF INNOVATIVE SYSTEMS FOR ENERGY PRODUCTION & CONTROL AND FOR SMART DEVICES Partners : ST Microelectronics, CEA, University of Bari to assess the possibility to integrate energy microsource, e.g. microbatteries, with MEMS or IC components, thus enabling new functions and serving new applications Irish Government programmes Pt-based catalyst development for methanol oxidation Higher methanol oxidation current Improved CO byproduct tolerance To be integrated into fuel cell in future project proposal Lithium based microbattery 3D microfabrication for improved current drain capabilities Microfabricated fuel cell borohydride based WSN application

Power Supply on Chip Discrete components Low Power DC/DC converter: Integration of passives on chip Inductor chip mounted on-top of the IC 100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% L/L2001 C/C2001 Frequency (Hz) Commercial Product 2001 2003 2005 2007 2009 Year 2.50E+07 2.00E+07 1.50E+07 1.00E+07 5.00E+06 0.00E+00 Frequency (Hz) Inductor fabricated directly on top of IC

Tyndall Inductor on Silicon: Basic structure of component Single layer of racetrack shaped copper coils sandwiched between layers of magnetic material Transformer - Interleaved primary and secondary windings Windings and magnetic core deposited by low cost electroplating magnetic core insulator II silicon substrate race-track shaped Cu windings insulator I Copper windings

Typical Inductor Characteristics Inductance_Ind50 Inductance_Ind50G Inductance_Ind70 Inductance_Ind70G Q Factor_Ind50 Q Factor_Ind50G Q Factor_Ind70 Q Factor_Ind70G 0.18 12 0.16 0.14 10 Inductance ( μ H ) 0.12 0.1 0.08 0.06 8 6 4 0.04 0.02 0 Inductance and Q-factor vs. frequency 0 0.1 1 Frequency (MHz) 10 100 2

Research Theme: Wireless Sensor Systems Research Focus: Hardware and Software Technology Platforms for Autonomous Wireless Systems Miniaturised Autonomous Wireless Microsensor Modules Distributed, Ad-hoc Wireless Sensor Networks Deployment in End-User Applications Hardware Features: Modular, Flexible, Reconfigurable, Scaleable, Robust Sensors Drivers / Controllers Data Processing Communications Power Tyndall 25mm Mote - Under Evaluation by >20 Research Teams in Ireland, Europe, USA.

Research Theme: Micropower for ICT Research Focus: Technologies for micropower generation/transmission, storage and conversion. Energy Source - Vibration Harvesting - Solar Cells - Piezoelectrics - Inductive Power - Microfuel cells Energy Storage - Microbatteries Power Conversion - Power Supply on Chip - Magnetics on Silicon

Research Theme: System Integration and Packaging Research Focus: Technologies for miniaturisation of wireless sensor modules. 25mm Cube to Sugar Cube to Intelligent Seed 25mm 10mm 5mm