Microcantilever-based weather station for temperature, humidity and flow rate measurement

Abstract

The current study develops a new process for the fabrication of Pt resistor temperature detectors (RTDs), cantilevers covered with a water-absorbent polyimide layer for humidity measurement and the bending-up of cantilevers to determine the flow rate. Pt RTDs are fabricated on the silicon substrate. The temperature measurement is based on the linear resistance variations when temperature changes. The polyimide layer is spun on the cantilever to form a humidity sensing layer. A variation in humidity causes moisture-dependent bending of the micro-cantilever, which changes the measured resistance of the resistor on the microcantilever. The same type of micro-cantilever, without spinning on polyimide, is used to form an anemometer. It is found that the cantilever bends slightly upward as a result of the released residual stress induced in the beam during the fabrication. When wind passes over the cantilever beam, a small deformation occurs. Variations in the flow rate can therefore be determined by measuring the changes in resistance caused by the beam deflection, using a LCR meter.

High-performance capacitive humidity sensor with novel electrode and polyimide layer based on MEMS technology

“…MEMS-based humidity sensors can be categorized into capacitive, resistive, mechanical, oscillating, and thermoelemental types based on the sensing principle (Su et al 2006;Yadav et al 2007;Smetana and Unger 2008;Ma et al 2008). Among these several types of humidity sensors, the capacitive device is preferred because of its linear sensitivity in a wide range of relative humidity (RH).…”

Fabrication and characterization of MEMS-based flow sensors based on hot films

“…150°C, due to its more rapid heat conduction and faster response to the flow rate. The non-dimensionalized sensitivity of the proposed single-chip flow sensor is 0.62%/ms -1 , which is Variations of measured resistance change of the double-chip flow sensors against the flow rate for a constant micro-heater temperature of 150°C: type A-the front resistor is the micro-heater and the rear resistor is the temperature detector and type B-the rear resistor is the micro-heater and the front resistor is the temperature detector higher than those of the previous studies (Tai et al 1985;Neda et al 1996;Ozaki et al 2000;Makinwa and Huijsing 2002;Kim et al 2004;Bruschi et al 2005;Ma et al 2006Ma et al , 2008Wang et al 2007). Figure 10 shows the time response obtained from the proposed double-chip and single-chip flow sensors at 150°C.…”

A Multiparameter Gas-Monitoring System Combining Functionalized and Non-Functionalized Microcantilevers

“…In this study, we focus on the feasibility of humidity measurement at ppm level on synthetic welding gas mixtures with functionalized micro-cantilevers in an industrial environment, which means that gas composition, temperature and pressure may vary and, therefore, the sensor must be able to work under non-ideal conditions. This is in contrast to most previous studies on this topic, where the behaviour of the sensors was investigated under very stable and controlled conditions [3][4][5][6].…”