K. Rajanna

Tactile sensor based on piezoelectric resonance

We discuss here the realization of tactile sensors based on the principle of change in piezoelectric resonance frequency with the applied pressure. An array of electrodes has been adopted on either side of the PZT material to have independent resonators. The common areas sandwiched between the electrodes and excitable at resonance frequency of the PZT material are used to form the sensitive area of the tactile sensor. The electrodes were deposited using sputtering technique. Tactile sensors with 3/spl times/3, 7/spl times/7, and 15/spl times/15 array of electrodes are developed with different electrode dimensions and separation between the electrodes. The tactile sensor has been interfaced to computer for the convenience of automatic scanning and making it more user interactive. The tactile sensors developed with different spatial resolution were tested for different shaped objects placed in contact with the sensor. The 3/spl times/3 matrix tactile sensor showed relatively poor spatial resolution, whereas the 15/spl times/15- matrix tactile sensor showed improved spatial resolution. The sensor with 7/spl times/7 matrix elements was tested for its sensitivity to different extents of applied force/pressure. The output response study carried out on the sensors indicated that these sensors can provide information not only about the extent of force/pressure applied on the object, but also the contour of the object which is in contact with the sensor.

Deep reactive ion etching of silicon carbide

In this article, we describe more than 100-μm-deep reactive ion etching (RIE) of silicon carbide (SiC) in oxygen-added sulfur hexafluoride (SF6) plasma. We used a homemade magnetically enhanced, inductively coupled plasma reactive ion etcher (ME-ICP-RIE) and electroplated nickel masks. First, 5 h etching experiments using etching gases with 0%, 5%, 10% and 20% oxygen were performed by supplying rf power of 150 and 130 W to an ICP antenna and a sample stage, respectively. They demonstrated a maximum etch rate of 0.45 μm/min and residue-free etching in the case of 5% oxygen addition. Observation of the cross sections of etched samples using a scanning electron microscope confirmed a microloading effect, which is reduction of the etched depth with a decrease in the mask opening width. Next, a 7 h etching experiment using an etching gas with 5% oxygen was performed by increasing the rf power to the sample stage to 150 W. This yielded an etched depth of 216 μm.

Pressure transducer with Au-Ni thin-film strain gauges

The behavior of a pressure transducer with Au-Ni (89:11) film as strain gauges has been studied. The effects of postdeposition heat treatment on the resistance of the thin-film strain gauges and hence the output performance of the pressure transducer are discussed. The effect of a repeated number of pressure cycles carried out over a period of eight months has also been reported. The maximum nonlinearity and the hysteresis is improved from 0.92% FSO to 0.06% FSO after 1000 pressure cycles. The output behavior of the pressure transducer with temperature has also been studied. >

Strain-sensitive property of vacuum evaporated manganese films☆

Manganese films have been studied with respect to strain gauge applications, and the criteria for choosing manganese are highlighted. The resistance-strain characteristics of the films have been studied in the thickness range 600–1600

Thin-film strain gauge sensors for ion thrust measurement

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Thin film strain gauge sensors for ion thrust measurement

. The in-situ variation in resistance of the films with temperature has been studied to estimate the temperature coefficient of resistance (TCR). It is found that for thicker films the TCR is around 3.35 ×

Thin-film pressure transducer with manganese film as the strain gauge

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Strain sensitivity and temperature behavior of invar alloy films

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Evaluation of transverse piezoelectric coefficient of ZnO thin films deposited on different flexible substrates: a comparative study on the vibration sensing performance.

. The other parameter that has been measured is the gauge factor and its variation with film thickness. The variation of TCR with film thickness is also reported. It is concluded that, since continuous manganese films exhibit better strain sensitivity (gauge factor is approximately 3) and possess a TCR an order of magnitude smaller than most other metal films, they are of potential use for strain gauge application.