Nanoenabled Self-Powered Sensor

Systems for Personal Health and

Personal Environmental Monitoring

Veena Misra

Director, NSF ASSIST Nanosytems Center

Professor of ECE

North Carolina State University

Korea-U.S. Forum on Nanotechnology

September 29-30, 2014

2 2010 2020

1960 1970

2000 1990

1980

3 Lung Pollution in China Thingprogress.org

Environmental

Factors

Chronic

Disease

Air Quality

Particulates

Gases

Heavy Metals

Chemicals

Noise

Organic Solvents

Inflammation

Oxidative Stress

Insulin Signal Disruption

Heart Disease

Arrhythmia

Lung Disease

Asthma

Brain

Alzheimers

Stress Biological Impact of Environmental

Triggers

Health + Environmental Link =

Exposure

4

Altered

Pathways

5

Medtronic, IEEE Spectrum 2014

ASSIST Vision

•Direct correlation of personal health and

personal environment

•Correlation of multimodal health sensing to

produce a systemic picture of wellness

6

The Wearable Health Market

7

FDA Approved

Consumer Products

Vital Connect

What are the gaps in these products?

Proteus Digital Health

Metria Patch by Vancive MC10 Hydration Sensor

Sotera Wireless FitBit

Nike Fuel

Piix Heart Monitor

Valencell

MISFIT ASSIST technologies can provide disruptive advances in existing wearable products and influence the future generation of wearable systems

Effectiveness of Wearable Health

Products is lacking

Most wearable's are not being used by 65+ older citizens Usage of sustained utilization drops below 50% in less then 15 months A third of the users stop wearing the wearable device within 6 months

Endeavor Partners, May 2014

Why is Effectiveness Low?

9

Form Factor/Design/A

esthetics

Battery Life/Hassle

Quality/Robustness/Medically Validation

Comfortable and biocompatible

Actionable Information/Multiple

Sensors

Open Platforms

Human and Social Factors/User

Feedback

Potential Solutions?

• The right multimodal, unobtrusive sensors for health and environment

• The data backbone supporting these sensors

• Medically validated / reliable sensor data

AND

• Ultra Low Power Components to enable ultra long battery lifetime

AND

• Energy harvesting energy to realize infinite lifetimes

10

Ultra Low Power Components

11

Computation

Communication

Sensors

Power Management

Interfaces

Nanotechnologies

Towards continuous monitoring

Body 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

Bio

com

pat

ibili

ty

Software

Software

Health Sensors

CO

TS A

dd

-on

Optimizing the Power for

Computation and Communication

12

Battery-free

Energy Harvesting ExG with MICS-Band Radio

0 2 4 6 8 100

0.5

1

1.5

time (s)V

olta

ge (V

)

RF Pulse, -10dBm

Boost Converter turns on

VBoost (on storage

cap)

VThermoElectricGenerator

0.13 µm CMOS

2.5

mm

3.3 mm

• 4 Channel ExG • MICS Radio • 5 DC-DC converters • MCU + Dig Accelerators • Integrated Power Management • MUCH more integration than any other wireless BSN SoC • Wireless RF pulse provides one-time kick-start • Runs indefinitely thereafter on thermal energy

Source: Calhoun et al., ISSCC 2012

Ultra Low Power SoC

14

EKG < 20mW relying only on energy harvesting and storage capacitors Boost converters < 10mV

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

0.4

0.6

0.8

1

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.5

1

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

0

0.5

1

1.798 1.7981 1.7982 1.7983 1.7984 1.7985 1.7986

0

0.5

1

1.7979 1.798 1.7981 1.7982 1.7983 1.7984 1.7985 1.7986 1.7987

0

0.5

1

655 ms

650 µs

Header Data CRC

VBoost

sample

ADC IN (V)

TX EN

TX DATA Time (s)

19µW total chip power from 30 mV input supply

Source: Calhoun et al., ISSCC 2012

Highlight: Measured Radio

Performance

Spec Value Unit

Power 7.44 µW

Data Rate 187.5 kbps

Center Frequency 3.8 GHz

Bandwidth 490 MHz

Output power --- dBm 15 Wentzloff, UMich

-60 -40 -20

100

1k

10k

Sensitivity [dBm]

Pow

er [μ

W]

Low Power Radios

Clock Harvesting Rx

-100 -800.1

1

10

UWB Rx

Wake Up Rx

ASSIST

ASSIST Receivers

• Best in class power vs sensitivity

• ~100nW Wakeup RX

ASSIST Ultra wideband (UWB) Transmit

• ULP TX for system level energy savings

960µm

1250µm

UWB

How low is ULTRA low when it comes to Power

ASSIST Antennas State of the Art

Form factor ~50mm x 50mm ~ twice as big

Front to back ratio ~19 dB (3X – 4X more range) ~ 5 dB

Signal suppression 3-5 dB (>50X less power) 20-30 dB

Out of band rejection 30 dB 5-10 dB

ASSIST Radios EnOcean STM 31xC IMEC ISSCC’14 Semtech SX1282

Supply voltage 0.5V to 1.0V 2.1V to 5.0V 1.2V 1.0V to 1.6V

TX power consump. 6µW @200kbps 30mW @ 125 kbps 4.6 mW ~40mW

RX power consump. 200µW WBAN RX 120nW @12.5 kbps WU

40mW 3.8 mW ~12mW

ASSIST SoC / processor EnOcean STM 31xC IMEC ISSCC’14 Semtech SX1282

Supply voltage 0.5V 2.1V to 5.0V 1.2V 1.0V to 1.6V

Processor 16b MSP430 custom 32b ARM Cortex M0 8b CoolRISC

Processor perf. <1µW @ 200 kHz 5.1mA @3-5V Not reported 1.2µW @ 32 kHz, 600 µW typical

Power harvesting Yes. RF, Solar, TEG Yes. No. No.

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Biochemical sensing

Cortisol, epinephrine

electrolytes/hydration

Gas/particulate sensing

Ozone, NOx, H2S, VOCs,

particulate matter

Bioelectrical sensing

ExG, hydration

Biophotonic sensing

Pulse oximetry Acoustic sensing

Body sounds

Nano-structured

MOx

Polymer coated

MEMS Hydrogel skin

interface

Polymer coated

sdAb

COTS microphone

Optical particulate sensing

AgNW

electrodes

Conductive

hydrogels Optical

TX/RX

Low-power

controller/radio

EnergyHarves ng

EnvironmentalSensor

SoC

RADIOAnalogFront

End

PowerManagement

DigitalControl/

Processing/Management

EnergyStorage

AntennaEnvironmental

Platform

EnergyHarves ng

SoC

RADIOAnalogFront

End

PowerManagement

DigitalControl/

Processing/Management

EnergyStorage

AntennaPhysiological

Platform

DataAggregator

Signal/DataProcessing

User

Medical / Off Body

Biocompa

bility

So ware

So ware

So ware

PhysiologicalSensor

COTSAdd-on

PhysiologicalSensor

Requires a systems driven, nanotechnology enabled

approach to realize low-power wearable sensors for

environmental and physiological monitoring

Asthma, cardiovascular health

Cardiovascular health Asthma

Stress, cardiovascular health

Hydration, cardiovascular health 17

Metal-oxide nanowire based gas sensors are

amenable to integration with CMOS

Sensors 2012, 12, 5517-5550

CMOS chip designed for MOx nanosensor

integration 18

Metal-oxide nanowire based gas sensors amenable

to integration with CMOS

Sensors 2012, 12, 5517-5550

MOx coated Si NWs self assembled on CMOS

19

Anatase TiO2 chemiresistor Rutile SnO2 chemiresistor

Crystalline metal-oxide-coated Si nanowires were fabricated using DRIE and ALD, and self-assembled on electrode arrays Self heating to 175°C with <20 μW power consumption is possible by thermal insulation

Silver nanowire electrodes on soft materials for

bioelectrical sensing

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pH <4.4 pH > 6.2 4.4<pH<6.2

PAAm Sweat Methyl Red

Color Spectrum

Peach pH Sensor

Used pH-color indicators to visually monitor diffusion

of acidic fluids (sweat mimics) through hydrogels

Hydrophilic Channels – Capillary Action

Superporous Hydrogel – Capillary

and Osmotic Sweat Intake

Superporous

Hydrogel –

Evaporation

Capillary Tube

SPH Gel

Hydrated (Body)

Gel

Time lapse

over

roughly 12

hours

Fluid transfer from superporous hydrogel to a capillary

Future Work: Create a Capillary-

Osmotic Pump for continual-

passive sweat intake

Sweat Diffusion

Establish a skin mimic for

interfacing and sensor testing

SPH

Membrane

Sweat

Solution

Usually used for drug

penetration; we will use for

sweat collection with various

skin (membrane) materials

Diffusion

Diffu

sio

n

Hydrogel-based noninvasive passive skin interfaces

for sweat sampling

21

Building the basic building blocks for a skin-coupled

biochemical sensor to monitor cortisol levels in

sweat

22

Intake rates via

osmotic uptake were

measured as ~15

nL/cm2min, much

greater than human

sweat rates (0.01 –

1 nL/cm2min)

sdAb-antigen stability at 400C for 7 days was demonstrated.

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6

-6.0x10-6

-4.0x10-6

-2.0x10-6

0.0

2.0x10-6

4.0x10-6

6.0x10-6

Cu

rre

nt (A

mp

s)

Potential (Volts)

sdAb

sdAb+antigen @ RT

sdAb+antigen @ 40C_7 Days

O O O

OAc

OAc

AcO

AcO

AcO

OAc

OAc

OO O O

OH

OH

HO

HO

HO

OH

OH

OH

O

TrehalosePolymer-1

O O O

OH

OH

HO

HO

HO

OH

OH

O

On

CN

Encapsulation of antibody with polymer/trehalose enables time

delayed dissolution of coating to expose one sensor at a time for

long term use

Potentiodynamic

electrochemical

measurements

using

functionalized

NW-enhanced

IDTs

Ionic hydrogel Microfluidic channel

interfaced to sensor

sites

Optional evaporation opening

Hydrogel for sweat

collection

Graded protective coating for timed release

Liquid metal electrode

Looking at both sides of the power equation Towards Self-Powered Operation

One harvester does not fit all?

24 iMEC

Energy Harvesting

This is a Very Difficult Problem to

Address for Human Worn Devices!

• Thermal: Small DT from human to ambient

• Mechanical: Weak base excitations at low frequencies for human

motion

• Indoor solar: 1 – 10 mW/cm2 available

• RF scavenging: << 1 mW from ambient rf. Much higher powers can

be achieved if directed rf is utilized.

• Inductive coupling: Tens mW available at close proximity

State of the Art Flexible

Thermoelectric Generators

26

Glatz et al., J MEMS 18, 763 (2009) Leonov, J. Micromech. Microeng. 21 (2011) 125013

Insulation area/(active material area)

Needs for flexible thermoelectric generators • Good materials (higher ZT) • Longer length (100 – 300 mm) than

typical film thickness for Bi2Te3

• Nanostructuring to decrease thermal conductivity

• Thermal resistance of harvester should be on order hundreds cm2 K / W

18.8 mW/cm2 K2

Flexible Thermoelectric Harvesters

Barrier: Parasitics (esp. skin resistance) have a huge impact

on TEG performance; output voltages ~ 5 – 30 mV

Maxim

um'Power'(uW)'

NCSUTEGSystemModel

Area=1.5cmx1.5cm50legs

w/ospreader

• Flexible, open-platform TEG package enabling integration of thermoelectrics with excellent performance from many sources

• Flexible, high performance heat sinks • New material & process approaches

Approach: To Increase Power

High ZT

Reduced Parasitics

Heat Collection

Heat Rejection 2

7

Thermoelectrics

• ~10 – 20 mW on a flexible hand-built package with COTS components

• Better Flexible package

• Reducing skin resistance is essential

• “Nano” in PbTe/PeTe1-xSex heterostructures, CNT-loaded polymers, ECD Bi2Te3 in alumina templates, hierarchical wicking structures

28

0

50

100

150

200

250

300

350

400

Walking

,Best

Skin

Staonary

,Best

Skin

Walking

,Wors

tSkin

Staonary

,Wors

tSkin

Maxim

umPower(uW)

ZT=0.8

ZT=1

ZT=1.2

ZT=1.5

TEG: 1.5 x 1.5 cm 50 legs

K = 0.8 – 1.5 W/mK

ApproachzTofbulkPbTe

zT of PbTe/PbSe0.2Te0.8

HighzTinshort-periodSLs

Non-Resonant Human Worn

Harvesters

29

Rotor

Magnets

Piezoelectric Plate

Housing

Measured prototype: 57 μW/cm2 peak power exceeds that of end-loaded cantilever on Si by > 35 times

Activity Walking Jogging Running

Power Available 95 mW 360 mW 700 mW

Power Density 10 mW/gram 37 mW/gram 74 mW/gram

Shad Roundy

Future Areas of Collaboration to Enable

Self-Powered Miniaturized Sensors

30

• Ultra low power electronics can change the sensing paradigm by enabling long term and continuous sensing

• Sensors innovation lies in lowering the power consumption and biochemical sensing

• Energy harvesting from the body is hard but is a worthwhile game changing technology • Thermoelectrics: Higher ZT, Flexible packaging, larger areas • Mechanical: need new designs including novel form factors (shoes, knees,

chest straps)

• Nano is creating advancements in sensor system components

• Samsung and KAIST (low power electronics, energy harvesting, sensors, flexible materials, manufacturing)

Thank you

31