Mems Sensors for Biomedical Applications
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Transcript of 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