Towards a miniaturized micromechanical electronic nose

Towards a
miniaturized
micromechanical
electronic nose
SYWERT H. BRONGERSMA
SR. PRINCIPAL RESEARCHER
© IMEC 2011
e-Nose: advanced sensing in complex environments
Human olfactory system
e-nose: array of non-specific, cross-reactive sensors
combined with an information processing system
Principal component analysis
4
Q4
PC2: 24.5%
Literature
examples
Propanol
2 Cyclohexanon
0
Q7
Q6
Q3
Q2
Q8
Q5
Anisole
-2
Toluene
Q1
-4
-4
© IMEC 2011
-2
0
PC1: 64.6%
2
4
2
Many Applications For e-Noses
State of the art commercial e-noses
• Gas Chromatography +
polymer coated SAW
• Response time 10 sec
• Listed price $14,950
7100 zNose
Miniaturization is
Electronic Sensor Technology (California)
needed for truly
• 32 polymer sensors
• Response time of 10 sec
portable e-noses!!!
• Weight ~1 kg (<2 pounds)
• Listed price is $7,995
Cyranose 320
Cyrano Science (Pasadena)
© IMEC 2011
Sensor Grand Challenges
State-of-the-art of e-Nose Sensors
Most
Disadvantages
Rule
These
Sensors
Out
for
Handheld
e-Nose
Applications
Sensors 2009, 9 5099-5148
© IMEC 2011
4
MEMS-based e-Nose For Organic Vapor Analysis
Vision
▸ Low-power electronic nose for organic vapors and metabolites
Advantages compared to state-of-the-art
▸ Small molecule detection possible
- Not only heavy bio-molecules also smaller vapors and gas molecules
- Enabled by combining well known mass effect with novel stress effect
▸ Low-power sensing
- No power consuming optical read-out required (piezo-electrics)
▸ Easily scalable
- No bulky optical instrumentation
- imec CMORE compatible fabrication
▸ Easy fabrication of sensor arrays
- Solves the intrinsic lack of selectivity in vapor detection
- Small form factor
- Multiple coatings using cheap mature inkjet printing
▸ Single technology
- Cheap
© IMEC 2011
L/hSi ≥ 100
hPoly ~ 2hSi
L ~ 100 µm
w ~ 6-10 µm
The working principle
Vapors
Beam
σ
σ
polymer
Adsorption
Extra mass
Swelling
Lower
Frequency
∆fn
∆m
αn ∆σ
Amplitude of Motion
Stress
Frequency
© IMEC 2011
6
From vision to reality
Die = 8.8 mm x 8.8 mm, 160 resonators
© IMEC 2011
7
Resonators Array Chip
Die = 8.8 mm x 8.8 mm, 160 resonators
© IMEC 2011
8
Ink Jet Printing Of Polymers On Suspended Beams
Backside printing
Using commercial printer
Custom prepared “ink” containing the specific polymer
50
Viscosity η [cP]
40
30
20
10
0
0
50
100
Concentration c [g/L]
PMMA
Coated
Uncoated
© IMEC 2011
9
Benchmarking
Commercial
w = 100 µm L = 500 µm h = 8 µm
Coating: PMMA
Detection: Optical Beam
w = 65 µm L = 750 µm h = 500 nm
Coating: PMMA
Transduction: Piezoelectric actuation/detection
Power = 2 mW
Power = 0.00017 mW (170 nW)
10.000 times more
power efficient
500
ppm
1500
ppm
1000
ppm
200
ppm
1-10 l/min
flow in 1.5 l
chamber
Ethanol
sensing
100 ml/min flow in 6 ml chamber
Frequency Shift ∆f [kHz]
0
-2
-4
-6
-8
N2
-10
0
10-5 frequency shift / %EtOH
260 times
responsivity increase
© IMEC 2011
100
N2
N2
200
300
Time [min]
N2
400
500
2.6 10-3 frequency shift / %EtOH
10
Co-optimization MEMS and IC Design
First results
MEMS resonator
Co-optimized
11
© IMEC 2011
First demonstrator
Resonators with integrated
transducers
Oscillator
based read-out
Integrated transduction
Enhanced sensitivity by 200x
~ 7 Hz/ppm
ppm detection capability
Testing the demonstrator
Resonance mode tracking
© IMEC 2011
12
SELECTIVITY BY COATING CHEMISTRY
Separation of alcohol and water vapors
Response to Ethanol
-0.5
-1
-1.5
0
Response to Humidity
0
Resonance Frequency Shift (%)
Resonance Frequency Shift (%)
0
PMMA-coated
PVA-coated
500
1000
1500
Concentration /ppm
© IMEC 2011
2000
-10
-20
-30
-40
Identical resonators
and operation modes
-50
PMMA-coated
PVA-coated
0
10
20
30
Humidity /%RH
40
< 13
SENSITIVITY & SELECTIVITY TESTING
Automated testing setup now operational
▸ Multi-device
▸ Multi-mode
▸ Multi-flow conditions
Allows for a lot measurements
© IMEC 2011
< 14
< 15
TRANSFER AND IMPLEMENTATION
Business case
Cost calculations
Packaging
Total MEMS area: 1.8 mm2
Oscillator circuit area: 2.6 mm2
Transferability of fabrication concept
Si
AlN
oxide
Failure mechanisms analysis
© IMEC 2011
Al
c-Si
SiC
e-Nose Applications Scenarios in Mobile Phones
Air quality monitoring and indoor air quality
control (pollution, malodor emission, toxic
gasses..)
CO2
high
levels
Ripeness, Food contamination
(spoilage, self live..)
Consumer fraud prevention
(ingredient confirmation, content standards..)
Taste, smell characteristics
(off flavors , product variety assessment..)
Pathogen identification
(patient treatment selection, prognosis..)
Physiological condition
(nutritional status, organ failure..)
Personnel and population security
(biological and chemical weapons...)
© IMEC 2011
The future is coming
Future: Year 2020?
NASA adapt iPhone
NTT DoCoMo
to smell chemicals
(Nov 17, 2009)
A Cell Phone that
spots Bad Breath
Nokia EcoSensor Concept
Nokia Scentsory Concept
Wearable sensor unit to sense
(environment, health..), and a
dedicated mobile phone (not an e-nose yet)
e-nose samples the odor of
caller environment and transmit
to recipient electronically
Other concepts:
Health conscious phone
that smells food properties
© IMEC 2011
© IMEC 2011