Capacitive micromachined ultrasonic transducers ~CMUTs!, introduced about a decade ago, have been shown to be a good alternative to conventional piezoelectric transducers in various aspects, such as sensitivity, transduction efficiency, and bandwidth. In this paper, we discuss the principles of capacitive transducer operation that underlie these aspects. Many of the key features of capacitive u...

Differing from the structure of traditional parallel plate capacitive sensor a semi cylindrical capacitive sensor has been introduced in this present work to measure the soil moisture conveniently. Here, the numerical analysis method to evaluate the capacitance from the semi-cylindrical capacitive sensor is analyzed and discussed. The changes of capacitance with the variation of soil moisture o...

Touch Sensing This is the detection and measurement of a contact force at a defined point. A touch sensor can also be restricted to binary information, namely touch, and no touch. Tactile Sensing This is the detection and measurement of the spatial distribution of forces perpendicular to a predetermined sensory area, and the subsequent interpretation of the spatial information. A tactile-sensin...

A new interface circuit for capacitive sensor is presented. This paper presents the design and simulation of soil moisture capacitive sensor interface circuit based on phase differential technique. The circuit has been designed and fabricated using MIMOS’ 0.35μm CMOS technology. Simulation and test results show linear characteristic from 36 – 52 degree phase difference, representing 0 – 100% in...

We report the capacitive spring softening effect observed in single-walled carbon nanotube (SWNT) nanoelectromechanical (NEM) resonators. The nanotube resonators adopt a dual-gate configuration with both bottom-gate and end-gate capable of tuning the resonance frequency through capacitive coupling. Interestingly, downward resonance frequency shifting is observed with increasing end-gate voltage...

 This paper analyses the mechanical behaviour of various suspensions of electrostatically actuated RF MEMS switches. A family of capacitive switches is described, with suspensions varying step by step from cantilevers to meander shaped double clamped beams. The result is a capacitive shunt switch with a designed actuation voltage of 4.5 V, and 20dB isolation and 0.04 dB insertion loss at a fre...

The paper discusses the importance and the issues of interfacing capacitive sensors. Two architectures applicable for interfacing capacitive sensors are presented. The first solution was designed to interface a capacitive humidity sensor designed and built for a humiditydependent monolithic capacitor developed at Budapest University of Technology and Economics. The second case presents the poss...

— This paper proposes a new circuit for capacitive sensing based on Dickson's charge pump. The proposed touch sensing circuit includes three stages of NMOS diodes and capacitors for charge transfer. The proposed circuit which has a simplified capacitive touch sensor model has been analyzed and simulated by Spectre using Magna EDMOS technology. Looking from the simulation results, the proposed c...

Capacitive technologies play an increasingly important role in the fields of industrial and automotive sensors. The noncontact working principle, on the one hand, is the main advantage of this technology; on the other hand, the sensor is thus sensitive to electromagnetic disturbances. This paper describes methods to successfully develop capacitive sensors, which can reliably be operated in hars...

A high accuracy switched capacitor, triple slope digital converter suitable for differential capacitive sensors is presented. The proposed technique accepts differential capacitive sensors possessing either linear or inverse characteristics and provides a linear capacitance to digital conversion. The output is dependent only on a pair of d.c. reference voltages and the clock frequency. Detailed...