Search

Thin film thermocouples were embedded in vertically to the rake face of cutting tools for better durability in temperature monitoring during titanium alloy cutting processes. • Tools embedded with thin film sensors to monitor cutting temperature. • Thin film thermocouples are embedded vertically to the tool face for protection. • Annealing treatment improved the quality of laterally deposited films. • Good sensitivity and fast responses are validated by experimental tests. • The vertically embedded sensors show good performance and reliability. Smart tools instrumented with thin film thermocouples for online cutting temperature measurement are promising in intelligent manufacturing. However, the surface-mounted planar devices are easily damaged through delamination and abrasion due to the high temperature, great stresses and harsh friction. This paper reports a novel approach to embed the thin film thermocouples in vertical direction to the tool rake face for protection. Attention is also paid to improve the quality of the vertically deposited thin films on the lateral walls of the micro-grooves. Experimental tests have been done to obtain the sensitivity and response of the sensors in the tool. The embedded sensors function well in monitoring the cutting temperature in cutting tests of a titanium alloy. [ABSTRACT FROM AUTHOR]

Abstract Sensors based on the detection of small resistance variations are universally recognized as piezoresistive. Being one of the simplest, most common and most investigated classes of sensors, continuous efforts are focused on creating improved devices with higher performance that can be used in many commercial and non–commercial applications (e.g. evaluation of strain, pressure, acceleration, force etc.). Consequently, despite the fact that more than 150 years have passed since the discovery of the piezoresistive effect in some classes of metals and semiconductors, the development of such sensors remains interesting and topical. Moreover, with the advent of second–generation robotics, research on piezoresistive sensors has undergone a massive increase. This paper aims to be a short, self–consistent vademecum which would be useful to researchers and engineers, since it focuses on the fundamentals of theory, materials, and readout–circuit design pertinent to the most recent developments in the field of piezoresistive sensors. [ABSTRACT FROM AUTHOR]

A generic method to reduce the in-line flow dependence of thermal conductivity detectors (TCDs) is presented. The principle is based on a dual-MEMS device configuration. Two thin-film sensors on membranes in parallel in the gas stream on the same chip are differentially operated. Both micro-TCDs are designed to be identical in terms of contact with the main gas flow, however a different depth of the detection chamber results in a different response to the thermal conductivity of the sample gas. Static and dynamic simulations have been performed to characterize the design of the fabricated structures. Devices have been fabricated in a MEMS process using a combined surface- and bulk micromachining process. The devices have been characterized statically and dynamically. Measurements on prototypes show that depending on the range of gases, device size and flow range device the effect of flow on the thermal conductivity can be reduced by a factor 4–15. [ABSTRACT FROM AUTHOR]

Deposited on a flexible skin, self-made MEMS (Micro Electronically-Mechanical Systems) thermal film sensors were applied to a contoured wall surface for sensing unsteady flow behaviors. The sensors, each featuring a platinum sensing element 0.1 μm in thickness on a polyimide substrate 20 μm thick, were about 150–200 ohm at room temperature. The frequency response of the sensors could be up to 30 kHz when operating in constant temperature mode. In studying the unsteady flow behaviors, the flow information of interest was mainly the frequency contents of the real-time signals measured. In this paper, the three presented cases illustrate how the signals of the MEMS sensors could be used to explore the instantaneous behaviors of the unsteady flows. [ABSTRACT FROM AUTHOR]

Abstract: This paper introduces a novel approach to the detection and accurate measurement of extremely small signals, produced by bilayer thin films without the use of sophisticated hardware. The implementation of this measuring system is based on the LabVIEW graphical programming. This general purpose, robust and low-cost signal detector, provides an excellent way to evaluate magnetostrictive materials and their application in magnetic sensors. Initially the complete system was first simulated in LabVIEW software with the simulated signal superimposed with noise signals and the correct performance of the program was successfully confirmed. Later the software was incorporated together with the simple modulating circuit of the sensor. The results from the acquisition proved that the system provides a quick and excellent way to evaluate magnetostrictive materials and their application in magnetic sensors. [Copyright &y& Elsevier]