Wireless Integrated Circuits and Systems for Advanced Implantable/Wearable Medical Devices

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1 Wireless Integrated Circuits and Systems for Advanced Implantable/Wearable Medical Devices Mehdi Kiani, Ph.D. January 2018 Integrated Circuits and Systems Lab () Electrical Engineering Department, Pennsylvania State University 47

2 Advanced Implantable Medical Devices: Brain Computer Interface and Bioelectronics Medicine BCI Electroceuticals 48

3 Integrated Circuits and Systems Lab () Research Projects Distributed Millimeter-Sized Brain Implants High-Resolution Implantable Gastric Interfacing Ultrasonic WPT Energy Harvesting Eyelid Drive System 49

4 Conventional Inductive Power Transmission Links Key Parameters: 1. Power Efficiency (η = η PA η Ind η PM ) for large V R 2. Voltage-Conversion Efficiency (VCE) = V L /V R,peak for small V R 50

5 Current-Mode Resonant Power Delivery (CRPD) t 0 < t < t 1 : SW is ON: Energy storage in the receiver inductor (L 2 ) t 1 < t < t 2 : SW is OFF: Power delivery to C L R L V R jumps to V D + V L! t 2 < t < t 3 : SW is OFF Sadeghi and Kiani, TCAS-I

6 Conventional Voltage- and Current-Mode Integrated Power Managements Structures/ Conditions Load (R L ) Receiver-Coil Voltage (V R ) Small Large Small Large Voltage-Mode (VM) Current-Mode (CM) Neither VM- nor CM structures can achieve the highest performance! 52

7 Proposed Voltage/Current-Mode Integrated Power Management (VCIPM) Concept VM CM Sadeghi and Kiani, ISSCC17, JSSC17 53

8 Adaptive Reconfigurable VCIPM Chip with Self-Regulation Sadeghi and Kiani, ISSCC17, JSSC17 54

9 Self-Regulation in Voltage Mode with Reverse Current Conventional Proposed Sadeghi and Kiani, ISSCC17, JSSC17 55

10 Over-Voltage Protection in Voltage Mode with Reverse Current Conventional Proposed 56

11 Measurement Setup and VCIPM Die 0.35-µm CMOS Freq. = 1 MHz V L = V DD = 3.2 V Sadeghi and Kiani, ISSCC17, JSSC17 57

12 Measurements: Input Power Variation in Voltage Mode (VM) R L = 100 kω Sadeghi and Kiani, ISSCC17, JSSC17 58

13 Measurements: VCIPM Mode Change R L = 100 kω Sadeghi and Kiani, ISSCC17, JSSC17 59

14 Measurements: Input Power Variation in Current Mode (CM) R L = 100 kω Sadeghi and Kiani, ISSCC17, JSSC17 60

15 Measurements: Maximum VCE in CM Max VCE = 3.5 V/V at R L = 100 kω, f sw = khz Sadeghi and Kiani, ISSCC17, JSSC17 61

16 Measurements: Range Extension R L = 100 kω VCIPM chip extended the range for 125% Sadeghi and Kiani, ISSCC17, JSSC17 62

17 Publication ISSCC CICC ISSCC ISSCC ISSCC This Work CMOS Tech (µm) Application WPT WPT WPT WPT Battery Charger WPT Rx Structure VM VM VM CM CM VM-CM Freq (MHz) Max VCE (V/V) 0.84/ ~ R @100 Max PCE P L (mw) Self-Startup Yes Yes Yes Yes No Yes Self-Regulation No Yes No No No Yes Range Extension (%) Line Regulation VM: (%) CM: 2.5 Load Regulation VM: < (%) CM: 2.2 Active Area (mm 2 ) ~4.77 ~ Over-Voltage Protection (OVP) No No No Yes No Yes Off-Chip Capacitors VCIPM Chip Benchmarking Sadeghi and Kiani, ISSCC17, JSSC17 63

Wrist-worn Harvester Challenges: Decaying

18 ASSIST Project: Efficient and Reconfigurable Circuit Interface for Multi-Modal Mechanical and Directed-Magnetic Energy Harvesting Wrist-worn Harvester Challenges: Decaying sinusoidal with small varying envelope Variable frequency Multi beams with unknown phases Modularity Dual modality Prof. Susan Trolier-McKinstry Prof. Shad Roundy 64

19 Reconfigurable Dual-Modal Shared- Intermediate-Inductor Harvesting Circuit 65

20 Acknowledgements Graduate Students Ahmed Ibrahim, Ph.D. Miao Meng, Ph.D. Hesam Sadeghi, Ph.D. Philip Graybill, Ph.D. Enhao Zhang, M.Sc. Funding Agencies National Science Foundation (NSF) National Institutes of Health (NIH) 66

Wearable Electronics with Conductive Textiles Active RF modules Jan

Our Team at FIU: Prof. Shubhendu Bhardwaj Prof. John Volakis Mr.

Jingni Zhong (Post-Doc) Electrical and Computer Engineering, Florida

21 Wearable Electronics with Conductive Textiles Active RF modules Jan 18th, 2018 ASSIST Industry-Day Meet, North Carolina State University Our Team at FIU: Prof. Shubhendu Bhardwaj Prof. John Volakis Mr. Dieff Vital (Grad Student) Dr. Jingni Zhong (Post-Doc) Electrical and Computer Engineering, Florida International University, Miami, Florida Passive antenna interfaces and power collectors Coupled RF systems

22 Potential Markets for Textile Electronics Concussiondetecting helmets Performance metrics (heart rate, oxygen levels, etc.) Sleep monitoring Location tracking Performance matrix tracking Integrated communication interfaces and sensing tactical gears Sensors/ Antennas integrated in Carseats/belts Enhanced WiFi/ GSM connection Integrated sensors in curtains, seats, carpets Security / Emergency Sensor-enabled Space Suits 68 Wearable Textile Electronics

Prior Technologies for Wearable Existing Sensors and wearables are rigid, breakable, bulky and obtrusive. Idea would be develop simple, integrative solutions on textile.

23 Prior Technologies for Wearable Existing Sensors and wearables are rigid, breakable, bulky and obtrusive. Idea would be develop simple, integrative solutions on textile. Future of wearables will rely of less (not more) complexity. Textile electronics suddenly provides whole lot of area to work with and in the form of clothes, its always in our vicinity. 69 Wearable Textile Electronics

24 Textile Technology at FIU Assistant Yarn Color option Can be Aesthetically worn Antennas (Low loss antennas) Conductive thread Cu core and Silver Coating 70 CAD Embroidery Machine RF to DC converters (efficiency more than 70 %) Communicatio n interfaces and Power Harvesting systems using RF Modules Antennas Wearable Textile Electronics

Ambient RF-Power Collection Use-cases Wifi routers

1 W power Cell phones emit anywhere between 0.

proximity with laptops, wifi routers Urban Outside

effective Power Availability scavenging strategies.

(with continuous video stream traffic) Further

25 Ambient RF-Power Collection Use-cases Wifi routers and Laptops typically emit 0.1 W power Cell phones emit anywhere between 0.5 W to 3 W of power In home environment, under close proximity with laptops, wifi routers Urban Outside environment Urban areas with large number of ambient radiators in close vicinity. Effective paradigm would require creative and effective Power Availability scavenging strategies. 71 Desk areas with larger wifi traffic Smart TVs, (with continuous video stream traffic) Further optimization via Strategic location of routers in frequently used areas Kitchen, bedroom etc. Wearable Textile Electronics

A Simple Test to RF Measure Power Spectrum Analyzer GSM 1900Wifi 2.

-30dBm TEXTILE Spiral antenna (2.4dB gain ) used in these test.

During Video Streaming GSM: -40dBm Wifi: -15dBm Higher power/ distances would be

26 A Simple Test to RF Measure Power Spectrum Analyzer GSM 1900Wifi 2.4G Ambient RF Power GSM: -40dBm Wifi: -30dBm During Phone Calls GSM: -10dBm Wifi: -30dBm TEXTILE Spiral antenna (2.4dB gain ) used in these test. Cell phone placed about 20cm from the spiral at broadside. During Video Streaming GSM: -40dBm Wifi: -15dBm Higher power/ distances would be realizable with higher gain + larger areas/gain+ polarization diversity + multiband antennas/harvesters 72 Wearable Textile Electronics

Large Area Textile Harvester (LATH)-Power Budget Power expectations of

Home / hospital environments Integration with other modalities of

Chris Rahn s) Certain Wearable use-cases communication allow further

27 Large Area Textile Harvester (LATH)-Power Budget Power expectations of upto mwatts range under Urban outside areas Busy internet usable. Home / hospital environments Integration with other modalities of harvesting Breath harvester system (Dr. Chris Rahn s) Certain Wearable use-cases communication allow further interfaces enhanced areas, SOC (Prof. allowing Doug more Werner power and collection Prof. Ben Calhoun) 73 Wearable Textile Electronics

28 Developments at FIU: High Efficiency Antennas Integrating ground planes via use of Multiplayer structures Passive antenna interfaces and power collectors 74 Wearable Textile Electronics

Measured Antennas (Patch) Extending the fabrication to

Measurements (FIU-Star Lab Chamber): high efficiency,

29 Measured Antennas (Patch) Extending the fabrication to multilayer structures. On-textile Patch Antenna, Fabricated :Dec 2017 / Jan 2018 Patch antenna implemented on Fabric. Measurements (FIU-Star Lab Chamber): high efficiency, agreement with simulation model 5 dbi gain / -30 db Matching on textile (numbers close to PCB) 75 Wearable Textile Electronics

30 Losses: PCB v/s Embroidered New design paradigm and manufacturing rules are to be uncovered. Our study concluded that losses in embroidered circuits is a function of direction of threads. Loss minimization with smart and strategic embroidery steps is desired. Loss levels ultimately can be brought down to PCB regimes. 76 Wearable Textile Electronics

Measured Antennas (Spiral no Ground plane)

2017 Measurements (FIU-Star Lab Chamber): high

31 Measured Antennas (Spiral no Ground plane) Single layer, but broadband spiral design for RF communication interfaces. On-textile Spiral Antenna, Fabricated :Oct/Nov 2017 Measurements (FIU-Star Lab Chamber): high efficiency, agreement with simulation model 77 Wearable Textile Electronics

32 Developments at FIU: Harvesters First Iteration of Circuits with peak efficiency upto 40% Second Iteration Harvester Circuits with Efficiency > 80% Nov, 2017 Jan, Wearable Textile Electronics

33 On Going Work and Imminent Developments Integrated Antenna + Harvester Systems Antenna Harvester Arrays for LATH Efforts: Array integration for large area harvester applications. Antenna miniaturization for enhanced packing density Power combining methods with other modalities Integration with Testbeds / wound healing. 79 Wearable Textile Electronics

More work to be done Conclusion: Conductive textiles have demonstrated, near PCB performance for small circuits and antenna interfaces. Efficient antenna / Harvesters already demonstrated.

34 More work to be done Conclusion: Conductive textiles have demonstrated, near PCB performance for small circuits and antenna interfaces. Efficient antenna / Harvesters already demonstrated. Expectation of 0.5 mw of power from array is realizable based on current data. Newly Established RFCOM-LAB at FIU engineering center Barriers/ Next Endeavors: Integration with test beds. Demonstrate real power generation and establishing effective use cases. 80 Wearable Textile Electronics

RF Energy Harvesting System from Cell Towers in 900MHz Band

RF Energy Harvesting System from Cell Towers in 900MHz Band Mahima Arrawatia Electrical Engineering Department Email: mahima87@ee.iitb.ac.in Maryam Shojaei Baghini Electrical Engineering Department Email: