Miniature Absolute Pressure Transducer

Period of Performance: 07/23/2003 - 04/23/2004

$100K

Phase 1 SBIR

Recipient Firm

Kulite Semiconductor Products, Inc.
One Willow Tree Road
Leonia, NJ 07605
Principal Investigator

Abstract

It is well known how expensive it is to run and conduct tests in a hypersonic wind tunnel. With air speeds of greater than mach 4 and as high as mach 10 the environment can often be very hostile. Because of the great difficulty of conducting measurements under these extreme conditions, any transducer so employed must be very small, very rugged, and able to obtain highly accurate data. It should be easy to install and remove, should not require re-calibration, should not require extensive pneumatic interconnects or long electrical wiring, and should, ideally, be low cost. Kulite is proposing to develop a miniature piezoresistive transducer of approximately .1 cubic inches in volume. The full-scale pressure of the proposed transducer will be 5 psia and suitable methods will be developed to obtain accuracies of .0025 psia. The sensor will be fabricated using Kulite's latest "leadless" silicon-on-oxide technology. This approach will enable the sensor to operate in excess of 900°F, have a natural frequency in excess of 250 KHz and withstand shock and vibration in excess of 100g. This amplified transducer will be terminated with a miniature connector for ease in assembling and disassembling it from the model. From a measurement systems viewpoint Kulite's approach has several anticipated benefits. First, the very small size of the transducer, coupled with its high temperature capability, enables the unit to be placed quite close to the pressure taps in small models. Second, the very small volume before the sensing diaphragm means that relatively high (100's of hertz) frequency response can be realized even when the transducer is mounted behind modest lengths (6-12") of hypodermic tubing. This results in very fast settling times and so increases the usable sampling rates. Third, the availability of digital and analog outputs from the same unit makes this an attractive solution for interfacing both with today's analog data systems and with future digital systems. Digital approaches, including data busses within the model, which may greatly simplify wiring complexity and model electrical interfaces, reduce noise, and increase usable bandwidth.