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Design criteria for flexible capacitive pressure sensors using DIYtechniques and household materialsAuthor: Rishabh Bhooshan Mishra Date: 2021-05-20 Report no: IIIT/TH/2021/51 Advisor:Aftab M Hussain AbstractThe flexible capacitive pressure sensors are one of the most essential and famous devices with vast applications in automobile, aerospace, marine, healthcare, wearables, consumer, and portable electronics. The fabrication of pressure sensors in a cleanroom is expensive and time-consuming; however, the sensitivity, linearity, and other performance factors of those pressure sensors are exceptional. Moreover, sometimes we require sensors that are not expensive and can be fabricated rapidly where the other performance factors don’t need to be highly remarkable. In this modern era, household materials and DIY (Do-it-yourself) techniques are quite helpful, highly utilized. They are recommended to fabricate low-cost sensors and healthcare devices for personalized medicine and low-cost consumer electronics. Different flexible capacitive pressure sensors are presented and experimentally characterized for acoustic and air-pressure monitoring in this thesis. The design criteria of a cantilever-based capacitive pressure sensor are discussed. The three different designs are analysed with aspect ratios of 1.5, 1.0, and 0.67. The sensor with an aspect ratio of 0.67 shows maximum sensitivity (mechanical and electrical), better response time, and the 1st and 2nd mode of resonant frequencies is comparatively less than the other two. The cantilever designs are susceptible to slight pressure; therefore, the diaphragm-based normal mode capacitive pressure sensor is introduced in the second chapter, which defines the design criteria of diaphragm shapes. The five different diaphragms analysed are circular, elliptical, pentagon, square, and rectangular shapes. The circular capacitive pressure sensor shows maximum sensitivity, however, maximum non-linear response. The rectangular capacitive pressure sensor has a maximum linear response; however, the sensitivity is the lowest. However, to design the pressure sensor for bit higher pressure monitoring and increase the linear output regime, we analyse the single and double touch mode capacitive pressure sensors. The single-touch mode capacitive pressure sensor shows linear response for 8 – 40 kPa however double touch mode capacitive pressure sensor shows the linear response for 14.24 – 54.9 kPa. The presented sensor offers high sensitivity and an accurate response; therefore, we can utilize these sensors for various applications like tire-pressure monitoring, hear-rate, asthma monitoring, etc. The capacitive pressure sensor is chosen because of its advantages like low-temperature drift, high sensitivity, and ease of design. Full thesis: pdf Centre for VLSI and Embeded Systems Technology |
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