Yes, there are better accelerometers out there. You may wish to look at "Survey
of Quartz Bulk Resonator Sensor Technologies," by EerNisse et al., IEEE Trans.
on Ultrasonics, Ferroelectrics and Frequency Control, v. 35, pp. 323-330, May
1988.

What dynamic range do you need? Quartz can give you micro-g resolution out of
20g full scale, and it's probably possible to do better (see ref's 49 & 50 of
EerNisse). Of course, temperature effects and noise are just two of the
problems to be dealt with in trying to sense 10 nano-g.

Quartz micromachining technology is nowhere near Si, but quartz has some
inherent advantages over Si in applications like this (e.g., quartz devices can
have zero temperature coefficient, and the lowest noise devices made by man are
quartz resonators). The trouble with both quartz and Si is that the smaller the
device, the noisier it gets, so you may not necessarily wish to use
micro-devices. For example, contamination adsorption and desorption will
produce significant noise (yes, even in a vacuum). See, for example, "Resonator
Surface Contamination - A Cause of Frequency Fluctuations?," Y. K. Yong and J.
R. Vig, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency
Control, Vol. 36, No. 4, pp. 452-458, July 1989, and "Modeling Resonator
Frequency Fluctuations Induced by Adsorbing and Desorbing Surface Molecules,"
Yook-Kong Yong and John R. Vig, IEEE Transactions on Ultrasonics,
Ferroelectrics, and Frequency Control, pp. 543-550, November 1990.

Good luck!.......................................John.
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           John R. Vig
           U. S. Army Research Laboratory
           Attn: AMSRL-PS-ED
           Ft. Monmouth, NJ 07703-5601, U.S.A.

Telephone: 908-427-4275,    FAX: 908-427-4805
Internet: JVig@ARL.mil
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