Resonant LGS microsensor for scanning microdeformation microscopy

Abstract

Scanning microdeformation microscopy (SMM) is a near field microscopy in the mesoscopic domain. Such a microscope has become an alternative to the high resolution acoustic microscope that operates at very high frequencies. SMM is based on a vibrating contact tip and piezoelectric detection. The lateral resolution is essentially related to the tip diameter. Classically, the SMM sensor is obtained by a complex mounting process. The tip is glued on a Si cantilever driven by a piezoelectric ceramic. Piezoelectric crystal is an alternative to get a monolithic vibrating cantilever. Quartz crystal, which is the most often used piezoelectric material, can be advantageously replaced by Langasite crystal because of its higher piezoelectric coefficients and its better temperature behaviour.

Langasite resonant structure: Micromachining and characterisation

“…For vibrating inertial sensors such as vibrating beam accelerometers (VBA) [3] or Coriolis vibrating gyros (CVG) [4], langasite is also an attractive piezoelectric crystal in comparison with quartz, thanks to its potential high quality factor and higher electromechanical coupling, predicting an improvement of the bias stability and the signal to noise ratio of the sensors [5]. Several application areas of MEMS can be initiated with this material [6,7]. In all cases, the miniaturization of the structure is of prime importance.…”

“…Some studies [8] reported in the literature concern the polishing of some LGS plates. Recent works have shown that among acidic etchants specific to LGS, the HCl [7], H 2 SO 4 [9] and H 3 PO 4 [10] based solutions offer the advantage of etch rates comparable to those obtained by quartz. So the first part of this paper is focus on the characterization of the anisotropic dissolution process in several different solutions based on HCl acid.…”