Xsense2

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X-Sense II Natural Hazard Warning

NanoTera Annual Meeting 2015 Michelle M端ller

Micro- and Nanosystems, ETHZ

Lothar Thiele Jan Beutel Andreas Vieli Alain Geiger Hugo Raetzo Christofer Hierold Cosmin Roman

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

X-Sense II Motivation

Objective

Randa, 22. April 2015

Micro and Nanosystems Group

New scientific knowledge about geophysical processes

Development of early warning system for rock fall detection

2

Wireless sensor networks in X-Sense I and X-Sense II

Micro and Nanosystems Group

3

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

4

Event-based sensing architecture Approach: move decisions to the front

Preprocessing

Raw sensor data

Communication

Data cleaning, system health

Data processing

Nano

Geophysical processes Tera

Event-based architecture Event-based architecture Service-energy proportional behavior

Micro and Nanosystems Group

5

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

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

8

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 9

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 themselves‌

Geophone + accelerometer

Amitrano et al., GRL 2005

~ 1 hour before

>200 micro-seismic events

Micro and Nanosystems Group

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

12

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., “Energy localization and frequency analysis in the locust ear�, 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

SEM close-up of spring m4

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

N8

Average amplification 2mm

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Micro and Nanosystems Group

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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

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 đ?’™đ?’†đ?’™đ?’• /đ?’… = đ?&#x;Ž. đ?&#x;Žđ?&#x;Žđ?&#x;’đ?&#x;’, a đ?’… ≈ đ?&#x;?đ?&#x;‘đ?&#x;Ž đ?’?đ?’Ž gap is required to achieve đ?&#x;? đ?’?đ?’Ž 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 1’000 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

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 20

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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