mems sensors for biomedical applications

7/28/2019 Mems Sensors for Biomedical Applications

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MEMS Sensors for BiomedicalApplications

Yu-Chong Tai

Professor of EE

Member of NSF/CNSE

California Institute of Technology

(NSF/ERC Industry Day, May 16-17, 2001)


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What is MEMS?

In US: Microdynamics

In Europe: Micro Systems (Technology)

In Japan: Micromachines, MicroRobots

A Micro-Electro-Mechanical System (MEMS) is abatch-fabricated

(microfabricated) system that contains both electrical and mechanicalcomponents with characteristic sizes ranging

from nanometers to millimeters.

Other Names


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Machine Size

nm m mm m km

ConventionalMachines

Micromachines

(MEMS)

Molecular (Nano)

Machines

Quantity


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Pressure Sensors

Nitride diaphragm Poly strain gauges

200 m


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Schlumberger Oil-Well Pressure Sensor

10,000 2 psi design

Multi-diaphragm configuration

4 nitride

DiaphragmsPolysilicon

thermistor

0.45

0.5

0.55

0.6

0.65

0 1000 2000 3000 4000 5000

Pressure (psi)

outputvoltage(V)


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MEMS Pressure Sensor Probe

for Intraocular Pressure Measurement

Pressure sensor

Sensor Tip

Flexible ribbon

Wafer with flexible

pressure sensor skins


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Vacuum-Insulated Shear Stress Sensor

Cross-section

Photograph

Polysilicon Wire

(3 x 150 x 0.5 m3)

Vacuum Cavity

(200 x 200 x 2 m3)

Polysilicon w ire

Nitride diaphragm

Vacuum cavity

Si substrate

Metal lead Metal lead


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Successful Test on NASAF 15

2.86 cm

1cm

Micro

Sensor

Stanton

Sensor

M=0.3

M=0.5

M=0.7

M=0.9

Time

Shear

Stress(Pa)

Shear-stress Sensor Imager


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2 cm

2 mm 1 mm

Pressuresensor

Temperaturesensor

Shear stresssensor

200m

Multi-sensor chip:

Pressure, Temperature and Flow

Five sensor clusters with a

pitch of 2 mm.

1

cm


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MEMS Mass Flow Meter

PCB

Inlet

N2

Bonding wires

Multi-sensor array chip

Channel chip

Schematic of packaged device

picture of a packaged device

Channel width: 2.5 mm

Channel height: 0.2 mm

Channel length: 18 mm

5.0

5.5

6.0

6.5

0.0 0.5 1.0 1.5

Q1/2.2

P(mW

)


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5.0

5.5

6.0

6.5

7.0

7.5

0 1 2 3 4 5 6 7 8 9 10

Q (SLPM)

Laminar

flow

Turbulent flow

Power(mW)

Calibration of the thermal flowmeter

Non-linear output


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Measurement of channel flow

0

0.5

1

1 2 3 4 5

Positon

(c ) Relative output change of shear stress sensors(a) Pressure distribution (b) Temperature distribution

24

24.5

25

25.5

26

1 2 3 4 5

Position

T(oC)

0

0.05

0.1

0.15

1 2 3 4 5

Position

V/V0

p(psig)

Measurement of fully developed incompressible channel flow (Mach number = 0.2 )

6

11

16

1 2 3 4 5

Position

(a) Pressure distribution

p

(psig)

25

25.5

26

26.5

27

1 2 3 4 5

Position

T

(oC)

(b) Temperature distribution

0.15

0.25

0.35

1 2 3 4 5

Position

V/V0

+(V/V0

)2/2

(c ) Relative output change of shear stress sensors

Measurement of fully developed compressible channel flow (Mach number = 0.6 )


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Microflow (l) Sensor

Top View

Bottom View


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Flow Rate Data

-0.007

-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0

0 200 400 600 800 1000 1200

Q [ul/min]

V

[V]

Water

Saline

30 mA

36 mW

Measures flow rates up to 10 l/min


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Flow Sensor Transient Data

0.7565

0.7570

0.7575

0.7580

0.7585

0.7590

0 100 200 300 400 500 600 700 800 900

Time [sec]

Voltage

[V]

No Flow & Intermittent Power


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Nanoflow (nl) Sensors

CavitySi ~100 m

20 m

Nitride

lightly B doped

polysilicon

2 m

heavily B doped

polysilicon

MicroChannel

Poly-Si

Sensors 200m

50 m 100m

SuspendedMicro

Channel

100 m


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-5

-4

-3

-2

-1

0

0 100 200 300

Q (nL/min)

T

(oC)

Temperature Change vs. Flow Rate

Channel on substrate

ST 0.0071oC/(nL/min)

Suspended channel

ST 0.026o

C/(nL/min)

Power 140W

Top 10 oC


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Sensor Resolution

Time-averaged Resolution nL/min

Histogram

0

2

46

8

10

12

14

2.034 2.035 2.036 2.037 2.038Sensor Output (V)

Fre

quency

2 2

GausianMeasurement


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MonocyteMonocyte Attachment through Molecular RecognitionAttachment through Molecular Recognition

Endothelial cells (EC)

flow

lipids trapped in arterial wall

monocyte attachment

lipids stimulate EC

Flow

Versatile Test Facility

0 1 2

sec

monocytes

0 1 2

sec


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Mon

ocytes/Field

MonocyteMonocyte AttachmentAttachment

Control Ox-PAPCOx-PAPC +

High slew Rate

Ox-PAPC +

Low Slew Rate

Ox-PAPC +

Oscillating Flow


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Other MEMS Applications


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30 m

full-grown cell

in neuron well

neurite growing in

micro-tunnel

gold

electrode

neuron trapping

canopy grillwork

Recorded Data

Hand-Fitted CurveVoltage(V)

time (msec)

Spontaneous Spike Recording

0 1 2 3 4 5 6 7 8 9 10

54

36

18

0

-18

-36

-54

-72

-90

-108Background 60 Hz averaged away.

Micromachined Neurowell


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Caltech MicromachiningGroup

Traditional ESI for Mass Spectrometry

Silica Capillary

Taylor Cone

MS inlet hole

MS

Inlet

air flow

Glass capillary 1-4 kV

particle filter

Spray stability dependson:

flow rate voltage distance

Vacuum

inside MS


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ESI Nozzle for Protein Mass Spectrometry

SEM of Capillary Tips

2.5 mm

600 800 1000 1200 1400 m/z

14+

15+

12+

13+

16+

17+

18+

19+

20+

21+

22+

23+

24+

25+

RelativeAbundance


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Caltech MicromachiningGroup

Taylor Cone Formation

15m

Solution: 1% Acetic Acid

49.5% Methanol

49.5% Water

Voltage: 800 V~ 1250 V

Distance: 500 m from electrode

15 m

800 V

15 m

950 V 1250 V

15 m


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On the Microbat ...

Fl i O i h


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Flying OnithopterMEMS Wings

Electric Motor

TransceiverAntenna

Acoustic Sensor Arrays

CMOS Imaging Array Autopilot Computer

BatteryPower Management

Electronics

Gearbox and

Transmission

Wing Control

Actuators

New MAV Design


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New MAV Design

Specifications

Weight: 12.5 g

Wing span: 9 inch

Flapping amp.: 65 deg

Flapping freq.: 20 Hz Flight velocity: 4 m/s

Power required: 2 W

Power source: Battery

Propulsion: Flapping Wings

mems sensors for biomedical applications

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