Project Title:

A 200 MHz Surface-Acoustic-Wave Resonator Micro-Deposition Monitor

92-1-08.26-6239                                                    NAS07-1228
A 200 MHz Surface-Acoustic-Wave Resonator 
     Micro-Deposition Monitor
Femtometrics
1001 West 17th Street, Suite R
Costa Mesa, CA  92627
W.D. Bowers                                          (714-722-6239)

Abstract:

     The quartz crystal microbalance (QCM) has been the accepted
instrument to monitor molecular deposition on a spacecraft surface
so that the level of surface contamination can be determined. The
mass sensitivity of the present QCM, 0.23 Hz cm2/nanogram for a 10
MHz crystal, cannot meet the 1 nanogram/cm2 required by NASA. A
new type of piezoelectric crystal, a 200 MHz surface-acoustic-wave
(SAW) resonator, piezoelectric crystal, could increase the mass
sensitivity two orders of magnitude over the conventional bulk
crystals. A 200 MHz, SAW-resonator, mass microbalance has been
developed for aerosol measurements and could be used to measure
microdepositions. With a sensitivity of 90 Hz cm2/nanogram, such a
SAW device can monitor the 1 nanogram/cm2 deposits with a
frequency shift of 90 Hz, which is about 400 times that of a
10 MHz bulk crystal (per unit area). By transferring the firm's
SAW mass microbalance technology and by using the existing QCM
technology, an efficient and cost-effective program is possible to
develop a small, lightweight, space-certifiable microdeposition
monitor.

Potential Commercial Application:

Potential Commercial Applications:  A small, lightweight, space-
certified, SAW-resonator microdeposition monitor would provide an
economical, compact, reliable, and extremely sensitive instrument
to measure molecular mass deposition in both vacuum chambers and
space simulation chambers, and in applications such as the space
station.

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