A flat type touch probe sensor using PZT thin film vibrator

We fabricated a touch probe sensor, having a flat configuration and using a PZT thin film vibrator. This sensor is intended for use in high-precision surface shape measuring tools at low contact force, for example, scanning probe microscopes (SPMs). The sensor consists of an oscillator vibrating in the longitudinal direction. According to our calculations higher sensitivity can be obtained by using longitudinal vibration than by using bending vibration. The vibration was excited and detected by a hydrothermally deposited PZT thin film device. The length of the vibrator was 9.8 mm, and its resonance frequency was 304.35 kHz. When the driving voltage was 3 Vp-p at the resonance frequency, the vibration amplitude at the tip of the sensor was 126 nm(o-p). We used the flat configuration and miniaturized the oscillator to increase the quantity ratio of piezo film in comparison to the base material, thus improving the sensitivity. The sensitivity and the resolution were evaluated experimentally, with the vertical resolution estimated to be 2.4 nm. This sensor device will be effective for use in high-speed and high-resolution surface shape measuring tools without damage to nano scale construction. (C) 2000 Elsevier Science S.A. All rights reserved.