Advanced Self-Powered Systems for

Integrated Sensors and Technologies

Antenna Low-Power

Sensors

Wearable Materials

Low-Power

Electronics Silicon-based

Platform

Energy

Harvesters

NSF Nanosystems Engineering Research Center for

Advanced Self-Powered Systems of Integrated Sensors and Technologies

(ASSIST)

Veena Misra, Director

2013 NSF Nanoscale Science and Engineering Grantees

Conference

December 6th, 2013

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ASSIST Vision

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Harnessing nanotechnology to improve global health by empowering patients and doctors to

manage wellness via personal health and personal environmental monitoring

ASSIST Impact

• Nano-enabled self-powered, wearable, wireless and comfortable sensor systems that enable:

– Health and environmental monitoring

– Improve management of wellness

– Enable correlation of health and environment

– Reduce global health costs by data driven medicine

– Translate technologies to industry to stimulate jobs

– Create an innovative and entrepreneurial workforce

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ASSIST is:

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Medically Relevant

Multiple sensors

Intelligent data

Reliable Devices

Adoption/Compliance

Hassle-free/self-powered

Non- or minimally-invasive

Wearable/comfortable

• A personal wearable and wireless health system

• Long term monitoring and correlation of personal health and personal environment

• Human powered which enables hassle free operation!

1

10

100

1000

10000

0.1 1 10 100 1000

Self-Reported Volume vs. Lifetime of Wearable Health/Fitness Monitors

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No volume info

Self Powered: Opportunity for

disruption

Volu

me (

cm

3)

Battery Lifetime (days)

• 95 products / projects, only 24 with lifetime data

• Self reported from data sheets

• Acquire some type of physiological data

• No comment on duty cycle, function

• State of Art: like an iPhone strapped to your body

Data from S. Lipa and P. Franzon

Self-Powered Going Beyond Fitness

• What medical conditions can truly benefit from long term monitoring

– Asthma (Lung function and Environment)

– Cardiovascular (Heart Rate Variability and Particles)

– Seizures

– Role of stress on wellness

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Intersection of Key Nanotechnologies

Self-Powered Systems for

Health

Heat, Vibration, Motion,

Biochemical

Nanoelectronics Revolution

Nano-enabled Energy Harvesting & Storage Revolution

Nanosensors Revolution

Hassle-free, long-term, wearable,

value added Body Heat

(2.4-4.8W)

Arm Motion

(60W)

Exhalation

0.40W

Heart Beat

0.01W

Finger Motion

0.76W-2.1mW Heel Strikes

(60W) 8

Nano-enabled ASSIST Systems

Nano is:

• Decreasing computational energy per bit.

• Increasing energy storage capability.

• Increasing energy harvesting efficiencies.

• Decreasing sensor power levels.

ASSIST Subthreshold CMOS and Beyond-CMOS devices

ASSIST Intelligent System Design and Radio

ASSIST III: Low-power

nanosensors

Current Thermoelectrics

ASSIST: Energy Harvesting and Storage

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From Nanocomponents to Nanosystems

10

Sense Process Communicate

Harvest Store Deliver/Manage

Data Flow

Power Flow

ASSIST Sensor Node Activities

Energy harvesters

Low-power Electronics

Low-Power Sensors

Silicon based platform Wearable materials

Antenna

What Nanosystems Provide

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Without ASSIST With ASSIST

Nano-enabled

Power Harvesting

Nano-enabled

Energy Efficiency

Nano-enabled

Sensor Power

Sensor Modalities

on one node

Node Lifetimes

< 75 μW

1 mW

5 adds / pJ

500 adds / pJ

100X

> 10X

5-10 mW

100 μW > 100X

Bioelectric

Bioelectric, pulse

ox, biochem,

gases, pH, …

Bioelectric: 7 days

Pulse ox: 1 day

Gases: < 1 day

Bioelectric:

Pulse ox:

Gases: not power ltd

Energy Harvesting

Gas Sensor

SoC

R A D I O Analog Front

End

Power Management

Digital Control / Processing / Management

Energy Storage

Antenna Health &

Environmental

Sensing

Platform

Physiological

Platform

Data Aggregator

Signal Processing

User B

ioco

mp

atib

ility

Software

Software

Health Sensors

CO

TS A

dd

-on

ASSIST Self-Powered System

• Thermoelectric Systems • Generate 200uWatts for Gen-1

• Piezoelectric Systems • Generate 30uWatts for Gen-1 • Build low voltage on TFT rectifiers • Initiate long-range motion for larger power

• Energy Caps • Beat COTs energy storage by Gen-1

• TFETs • Predict performance of TFETs in ASSIST SOC

• Sensors • Low power sensors • Multifunctional • Biochemical

• Low power SOC • Minimize power consumption

• Radios • Ultra low power radios that communicate with

base station (eventually smartphones) • Antennas

• Thin and wearable antenna • Wearability

• Robust, reliable and comfortable • Smartphone and Data Management

• Algorithms and Apps • Medical Validation / Feasibility

• Measure and start building databases for analysis

• Correlation • Engage EPA

• Translation of Center IP • Industry ecosystem

Green: clear impact on system demonstration using ASSIST’s unique advantage

ASSIST System Approach

Platform Development:

• Material integration/optimization to body

• In-lab testing alpha & beta testing

(reliability, durability)

• Biocompatibility

Signal and Information Processing:

• Data management

• Data correlation, analysis

System Optimization:

• Next Gen platform design, materials

development, & applications

• Testing (skin-package, package to

device)

• Social factors for acceptability &

relevance

Clinical Application:

• Pre-trial testing

• Trial planning

• Data! Data! Data!

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Iterative Cycle: 1. Assess research. 2. Refine system and application specs

and requirements.

Technical Barriers

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• Energy Harvesting and Storage – Reducing systems losses for Thermoelectrics

– Increasing power levels from Piezoelectrics

– Increasing energy density for supercapacitors

• Low Power Nanodevices – Achieving Heterogeneous Integration

• Wearable Nanosensors – Targeting sensor robustness/quality/reliability

– Reducing the sensor power levels for new modalities

• Lower power communication and computation – Maintaining low power while increasing functionality

• Systems Testbed Integration – Achieving Medical and environmental relevance

– Reducing form factors with comfortable and biocompatible materials

– Gaining industry prevalence and speed in producing wearable medical devices

– Addressing Big Data and complexities in data management

Cu Cu

Flexible TEG Process Development Flexible High Performance Heatsink

Carbon Nanotube Heatsink

1) Large Surface Area

2) High Thermal Conductivity

CNT

s

1 mm

RIE in CF4 + O2

Copper Electrochemical Deposition

Solid Diffusion Bonding

Human Body

Carbon Nanotube Heat Sink - Grown on Si,

transferred to Copper

Gen 2 & Beyond Objectives

BiTe Nanowires by ECD 1) Selective growth 2) High growth rates at low temperatures 3) Nanowires through templates

p p n n

substrate

Kapton

Ethylene + H2 + H2O at 750oC

Hierarchical Nanostructured Heat Pipe for Enhanced Two-Phase Heat Transfer

• Goal: Develop hierarchical wicking material with improved fluid/heat transfer properties for next-generation heat pipes

Removes heat and maintains temperature gradient across

thermoelectric generator using two-phase heat transfer

Chao

Results from PZT/Ni Energy Harvesters

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0

10

20

30

40

50

60

70

80

90

0.0E+00 2.0E+05 4.0E+05 6.0E+05 8.0E+05 1.0E+06

Max

imu

m P

ow

er

[μW

]

Resistance [Ω]

1.1g 1.5g 1.2g

1.0g 0.8g 0.5g

• Harvesters with resonance frequencies from 50 – 75 Hz prepared with PZT from 1 – 3

mm thick

• Thicker PZT films produce higher output powers and voltages

0

10

20

30

40

50

60

70

40 60 80 100

Max

. Po

we

r [μ

W]

Frequency [Hz]

1.0g

Resonance Frequency (Hz)

Optimal Load Resistance (kΩ)

Base Acceleration Input (g)

Output Volt. (mV)

Output Power ()

Experiment 50 30 0.3 515 8.84

Model 52.1 32.5 0.3 552.6 9.41

Base Acceleration Input =

Load Resistance

= Beam displacement output

+ V(t) - I(t)

Power output = V(t)I(t)

Proof mass

PZT Unimorph

Mechanical Harvesters Next Steps

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• Decreasing resonance frequency to ~ 10 Hz

• Utilizing mechanical nonlinearities to increase bandwidth

• Strain-based harvesters

Compliant mechanism design amplifies inertia to lower natural frequencies.

Flying bridge design provides efficient mode shape.

High Power at Low Frequency Thin sections

produce flexures or compliant

hinges

Base Acceleration Input

PZT Unimorph Bridge

Proof Inertia

Parabolic Mode Shape

Energy Storage Strategy

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ASSIST target space

Goal: Energy Storage

Objective: 1000J/cc

ASSIST Energy Storage Strategy

20

50 µm

Solid state high power CNT based

electrochemical capacitor capable

of being cycled beyond 10,000

cycles at 5 A/g was fabricated

• Improving Energy Density

• Combine double layer

electrode with faradaic

electrode

• Increase voltage window by

developing high purity C electrodes

• Improve power performance by

composite electrolytes

• Increase cyclability by developing

stable electrode/electrolyte

interfaces

Already demonstrated 100J/cc with

the ultimate goal of 1000J/cc

Low Power Computation Strategy • SoC for ASSIST platforms based on subthreshold CMOS

with average power < 30microwatts for continous use an world record boost converter input voltages

– Pull nanocomponents into working system

• Electronics for Gas sensing

• Power management for energy harvesters

• gets us a lot of power savings

• Beyond SubVT CMOS What’s next?

– TFETs

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Figure 10 Schematic band-diagram of (a) homojunction (b) staggered-gap heterojunction and (c)

broken gap heterojunction TFETs

-0.50 -0.25 0.00 0.25 0.50 0.750

10

20

30

40

50

60

Homojunction TFET

Drain

Cu

rren

t, I

DS [m

A/m

m]

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

Lg=150nm

Toxe=2.3nm

-0.50 -0.25 0.00 0.25 0.50 0.75

25

50

75

100

125

150

Drain

Cu

rren

t, I

DS [m

A/m

m]

Lg=150nm

Toxe=2.3nm

Staggered Heterojunction TFET

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

-0.50 -0.25 0.00 0.25 0.50 0.75

50

100

150

200

250

300

Drain

Cu

rren

t, I

DS [m

A/m

m]

Lg=150nm

Toxe=2.3nm

Broken Gap Heterojunction TFET

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

Figure 11 Measured output (IDS-VDS) characteristics of (a) homojunction (b) staggered-gap

heterojunction and (c)broken gap heterojunction TFETs showing increase in drive current with

increasing stagger.

Near Broken Gap

Figure 10 Schematic band-diagram of (a) homojunction (b) staggered-gap heterojunction and (c)

broken gap heterojunction TFETs

-0.50 -0.25 0.00 0.25 0.50 0.750

10

20

30

40

50

60

Homojunction TFET

Drain

Cu

rren

t, I

DS [m

A/m

m]

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

Lg=150nm

Toxe=2.3nm

-0.50 -0.25 0.00 0.25 0.50 0.75

25

50

75

100

125

150

Drain

Cu

rren

t, I

DS [m

A/m

m]

Lg=150nm

Toxe=2.3nm

Staggered Heterojunction TFET

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

-0.50 -0.25 0.00 0.25 0.50 0.75

50

100

150

200

250

300

Drain

Cu

rren

t, I

DS [m

A/m

m]

Lg=150nm

Toxe=2.3nm

Broken Gap Heterojunction TFET

Drain Voltage, VDS

[V]

VGS

=0 to2.5V

steps of 0.5V

Figure 11 Measured output (IDS-VDS) characteristics of (a) homojunction (b) staggered-gap

heterojunction and (c)broken gap heterojunction TFETs showing increase in drive current with

increasing stagger.

Near Broken GapHeterojuntion Tunnel FET

Breakthrough TFET Performance

High-k

Pd (gate)

N+ In0.9Ga0.1As

(drain)

i-In0.9Ga0.1As

(channel)

P+ GaAs0.18Sb0.82

(source)

Mo

ILD

100nm

Demonstration of near broken-gap tunnel

field effect transistors (NBTFETs) with a

200nm channel length that exhibited record

drive current (ION) of 740µA/µm, intrinsic

RF transconductance (GM) of 700µS/µm

and a cut-off frequency (FT) of 19GHz at a

source-drain voltage (VDS) of 0.5V.

IEDM 2013

Low Power Communication

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Need Ultra Low Power Transmission

• UWB transmission (1Mb/s at

4GHz) ~30mW

• WBAN receiver (200kb/s at

400MHz)

• Basestation for interface to these

radios

• 100nW wake up receiver to

remotely wake up from deep

sleep and for reprogramming the

SoC wirelessly.

• RF harvester to kick-start PMU

• Corresponding antenna

development (form factor!)

Opportunities in Sensing

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Eric Topol, Transforming Medicine through digital innovation” Science translational

medicine, Vol. 2, Issue 16, Jan 2010

BodyMedia

Available Sensing Modalities

• Biophysical/Inertial Sensors

• Bioelectronic Sensors

• Biochemical Sensors

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Accelerometer

Gyroscopes

Touch Sensor

Hall Sensor Gas Sensors

Humidity Sensor

Temp Sensor

Microphone Sensor

Image Sensor

GPS Sensor

Heart Rate/ExG Sensor

Pressure Sensor

Mature

Not Mature

ASSIST Low Power Sensing Strategy

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Ozone, NOx,

H2S, VOCs,

Particulate

Matter

Gas/Particulate

Sensing

Cortisol,

Epinephrine

Electrolytes/

Hydration

Biochemical

Sensing

EKG,EEG,

EMG, Skin

Conductivity/

Hydration

Bioelectrical

Sensing

Pulse

Oximetry,

Glucose,

Body

Sounds

Optical and Other

Sensing

Ultralow Power, Compact/Comfortable Form Factor,

Multifunctionality

Ultra low power

operation via

optimized ALD

and nanowires

Dry and Multifunctional

Electrodes System optimization

Device based

Non-invasive

reversible

COTS

Accelerometers

Microphones

Building Systems from nanowires

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Requirements: Integration and Packaging

• Comfortable, Flexible and Reliable

– Textiles based platforms, 3D Printing

• Modular

– Swap out sensors but not expensive harvesters or SoC

• Non-adhesive, clean

– Dry contacts

• Form factor and exploring new form factors

– Designed to optimized all available real estate

• Good interfacial properties – Thermal, biocompatible, mechanical

conductor

• Acceptable by the user

– Human factors studies

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Inter-Thrust Dependence

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Thrust V and Thrust I: size of

harvesters and storage caps

Thrust V and Thrust IV: Antenna, Chip

Size, Algorithm development

Thrust V and Thrust III: Sensor sizes,

packaging requirements, form factors

Thrust V and Thrust II: Novel Antenna

designs, TFET Analog

Thrust II and Thrust IV: TFET Analog,

Compressive sensing algorithms

Requires constant communication across the Center

Acceptability Testing Provides Considerable Benefits:

Assesses motivators and barriers of new technology use.

Linked to increased consumer spending.

Acceptability increase health utility in patients and providers.

Results in fewer redesigns, decreased costs of production

Allows varied acceptability parameters: physicians, patients, etc.

ASSIST Example Questions:

A full analysis of these will also assess differences in preference by age, education, gender, region, culture/ethnicity, etc.

Research Trusts - ASSIST Interrelated engineering projects

harness nanotechnology to improve health, using environmental sensors.

Prototype testing w/ Clinicians and

Families

Nano Tech Knowledge and

Preferences Survey

Results in Dynamically-tested Devices

Tested for social and behavioral knowledge and

preference contexts

Two-way Feedback:

Consumers and Engineers

Medical Device Feedback Clinicians

and Consumers

Motivations for extended use?

What should it look like?

Part of the body preferences?

How long to wear it?

What should it feel like?

Should device be visible to

others? Privacy?

Cost?

Perceived risks? Benefits?

Battery life expectations?

Social Factors Wearable Sensor Acceptability Testing:

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From Nanosystems to Products! ASSIST Industry Partners

Energy Harvesting

Nano-Devices

Sensors

Ultra Low Power Chip Design

Wearable Systems

Health & Wellness

ASSIST’s Industry

members provide

coverage across the

entire supply chain

Conclusions

• Self Powered operation is hard

• ASSIST is addressing the right things: PH ↑, Estorage↑, PLOAD ↓

• Self Powered operation is STILL hard and REQUIRES Systems Driven Approach

• Interaction with nano, materials, system, medical experts Cutting edge components

• Intelligent system and architecture design

• Adaptive power management algorithms

• Interaction with and advice from cutting edge industry

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Backup

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