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Microfabricated Ice-Detection SensorKnowledge of ice conditions on important aircraft lift and control surfaces is critical for safe operation. These conditions can be determined with conventional ice-detection sensors, but these sensors are often expensive, require elaborate installation procedures, and interrupt the airflow. A micromachined, silicon-based, flush-mounted sensor which generates no internal heat has been designed, batch fabricated, packaged, and tested. The sensor is capable of distinguishing between an ice-covered and a clean surface. It employs a bulk micromachined wafer with a 7 micrometer-thick, boron-doped, silicon diaphragm which serves as one plate of a parallel-plate capacitor. This is bonded to a second silicon wafer which contains the fixed electrodes, one to drive the diaphragm by application of a voltage, the other to measure the deflection by a change in capacitance. The diaphragm sizes ranged from 1x1 mm to 3x3 mm, and the gap between parallel-plate capacitors is 2 micrometers. A 200 V d.c. was applied to the driving electrode which caused the capacitance to increase approximately 0.6pf, from a nominal capacitance of 0.6pf, when the surface was ice free. After the sensor was cooled below the freezing point of water, the same voltage range was applied to the drive electrode. The capacitance increased by the same amount. Then a drop of water was placed over the diaphragm and allowed to freeze. This created an approximately 2mm-thick ice layer. The applied 200V d.c. produced no change in capacitance, confirming that the diaphragm was locked to the ice layer. Since the sensor uses capacitive actuation, it uses very little power and is an ideal candidate for inclusion in a wireless sensing system.
Document ID
19970025167
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
DeAnna, Russell G. (Army Research Lab. Cleveland, OH United States)
Mehregany, Mehran (Case Western Reserve Univ. Cleveland, OH United States)
Roy, Shuvo (Case Western Reserve Univ. Cleveland, OH United States)
Zakar, Eugene (Army Research Lab. Fort Monmouth, NJ United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1997
Subject Category
Aircraft Instrumentation
Report/Patent Number
E-10690
NASA-TM-107432
NAS 1.15:107432
ARL-TR-1355
Meeting Information
Meeting: Smart Structures and Materials
Location: San Diego, CA
Country: United States
Start Date: March 2, 1997
End Date: March 6, 1997
Sponsors: International Society for Optical Engineering
Accession Number
97N24790
Funding Number(s)
PROJECT: RTOP 523-26-13
PROJECT: DA Proj. 1L1-61102-AH-45
CONTRACT_GRANT: DAAL03-91-C-0034
CONTRACT_GRANT: DAAH04-95-10097
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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