X-Sense II
Natural Hazard Warning
NanoTera Annual Meeting 2015 Michelle M端ller
Lothar Thiele Jan Beutel Andreas Vieli Alain Geiger Hugo Raetzo Christofer Hierold Cosmin Roman
Micro- and Nanosystems, ETHZ
Computer Engineering ETHZ Computer Engineering ETHZ Physical Geography, UZH Geodesy, ETHZ Federal Office for the Environment Micro- and Nanosystems, ETHZ Micro- and Nanosystems, ETHZ
micro and nanosystems
Objective
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Micro and Nanosystems Group
n etcio fald
ces ro p Randa, 22. April 2015
X-Sense II Motivation
Wireless sensor networks in X-Sense I and X-Sense II
Micro and Nanosystems Group
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What is preventing wide applicability? Sensing movement events and/or micro-seismic and acoustic activities big data
high energy
Micro and Nanosystems Group
high cost
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Event-based sensing architecture Approach: move decisions to the front
Preprocessing
Raw sensor data
Communication
Data cleaning, system health
Data processing
Geophysical processes
Nano
Tera
Event-based architecture Event-based architecture Service-energy proportional behavior
Micro and Nanosystems Group
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X-Sense II Overview System design and integration
Computer Engineering and Networks Laboratory, ETHZ
MEMS acoustic emission sensor
Micro and Nanosystems Group, ETHZ
Knowledge about geophysical processes
Physical Geography, UZH Micro and Nanosystems Group
Event-based GPS
Institute of Geodesy and Photogrammetry, ETHZ 6
X-Sense II Overview System design and integration
Computer Engineering and Networks Laboratory, ETHZ
MEMS acoustic emission sensor
Micro and Nanosystems Group, ETHZ
Knowledge about geophysical processes
Physical Geography, UZH Micro and Nanosystems Group
Event-based GPS
Institute of Geodesy and Photogrammetry, ETHZ 7
Obtaining knowledge about geophysical processes… Various sensors to monitor environmental conditions: temperature sensors, weather stations, cameras Various sensors to monitor rocks: PermaSenseL1-GPS (large scale)
ForaPot crackmeter (small scale)
Daily position accuracy:
1-2 mm horizontal 3-5 mm vertical
Wireless communication
Acoustic/micro-seismic sensor (scale freq. dependent)
Potentiometric measurement principle Very high accuracy (≤ 0.01 mm) Temperature-compensated
Micro and Nanosystems Group
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Measurements with crackmeter
Micro and Nanosystems Group
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X-Sense II Overview System design and integration
Computer Engineering and Networks Laboratory, ETHZ
MEMS acoustic emission sensor
Micro and Nanosystems Group, ETHZ
Knowledge about geophysical processes
Physical Geography, UZH Micro and Nanosystems Group
Event-based GPS
Institute of Geodesy and Photogrammetry, ETHZ 10
MEMS acoustic emission sensor Development of a MEMS ultra-low power acoustic emission trigger Specifications
Micro and Nanosystems Group
Detection of 1 mg acceleration < 100 μW power consumption Frequency selective to signals between 5 - 20 kHz
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Destructive processes announce themselvesâ&#x20AC;Ś
Geophone + accelerometer
Amitrano et al., GRL 2005
~ 1 hour before
Micro and Nanosystems Group
>200 micro-seismic events
collapse
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MEMS ultra-low power AE trigger: Device concept Acoustic emission signals
Events
A coupled mass-spring system enables Purely mechanical amplification of incoming vibrations Frequency selectivity at zero power expense Spectral amplification with 16 coupled masses
Threshold-detection by an electro-mechanical trigger features Static threshold control instead of power intensive sampling at high frequencies High on-off ratios Reduced computational load
Pull-in • mn >… > m1 • kn/mn = … = k1/m1 Micro and Nanosystems Group
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Passive mechanical broadband amplifier: Modeling
1 cm
Mass
Shoaling effect Spring
Lateral view of thin springs
Package, moves with ground (not shown in Comsol model)
Malkin et al., â&#x20AC;&#x153;Energy localization and frequency analysis in the locust earâ&#x20AC;?, J. R. Soc. Interface, 2014. Micro and Nanosystems Group
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Passive mechanical broadband amplifier: Fabrication Device layer
Spring
Anchor Springs m1
Bulk m2
10Îźm
m3 m4
SEM close-up of spring Microscope picture of fabricated structure with 4 400 Îźm masses (N4) Micro and Nanosystems Group
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Passive mechanical broadband amplifier: Characterization N4
Transfer function 0
f [kHz] for N4 (f0 = 13 kHz) 6.5 13 19.5 N4
N8
Average amplification
2mm
26
2mm
Micro and Nanosystems Group
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N8
MEMS ultra-low power AE trigger: Device concept Acoustic emission signals
Events
A coupled mass-spring system enables Purely mechanical amplification of incoming vibrations Frequency selectivity at zero power expense Spectral amplification with 16 coupled masses
Threshold-detection by an electro-mechanical trigger features Static threshold control instead of power intensive sampling at high frequencies High on-off ratios Reduced computational load
Pull-in
Micro and Nanosystems Group
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Pull-in contact switch Operation principle: When the attractive electrostatic forces exceed the restoring spring force the system is pulled in catastrophically.
Pull-in If the movement amplitude becomes too large the attractive electrostatic forces become dominant and the proof-mass snaps in.
At threshold , a gap is required to achieve threshold
Micro and Nanosystems Group
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1st pull-in trigger Cut-out for LDV Spring
Proof mass
< 3Vpi for battery operation On-off ratio in the order of 1â&#x20AC;&#x2122;000 Micro and Nanosystems Group
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MEMS ultra-low power AE trigger: Device concept Acoustic emission signals
Events
Cut-out for LDV
?
Spring
Proof mass
400 Îźm
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MEMS ultra-low power AE trigger: First design study 4-coupled masses: amplification 17.3x Center-mass is connected to pull-in readout: Estimated sensitivity 2.5 Ă&#x2026; m1 m2 m3
m4 m1 Bondpad/stator
m2
Contacts
m3
Combdrive m4 21
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X-Sense II Overview System design and integration
Computer Engineering and Networks Laboratory, ETHZ
MEMS acoustic emission sensor
Micro and Nanosystems Group, ETHZ
Knowledge about geophysical processes
Physical Geography, UZH Micro and Nanosystems Group
Event-based GPS
Institute of Geodesy and Photogrammetry, ETHZ 22
Conclusion
Micro and Nanosystems Group
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Thank you for your attention! People Dr. Jan Beutel Bernhard Buchli Reto Da Forno Prof. Dr. Alain Geiger Dr. Lucas Girard Dr. Stephan Gruber Tonio Gsell Dr. Andreas Hasler Prof. Dr. Christofer Hierold Roland Hohensinn Roman Lim Dr. Philippe Limpach Verena Maiwald Fabian Neyer Hugo Raetzo Dr. Cosmin Roman Felix Sutton Prof. Dr. Lothar Thiele Prof. Dr. Andreas Vieli Christoph Walser Samuel Weber Vanessa Wirz Zhenzhong Su Micro and Nanosystems Group
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