The purpose of this application note is to describe the best design practices when developing capacitive touch applications for noisy environments. This application note will begin by defining the problems caused by noise, and explain how that noise typically affects systems. Hardware guidelines will then be provided to help maximize the natural signal-to-noise ratio (SNR) of the application. S...

You work in a characterization laboratory af a MEMS company, and you have to design an electronic board in order to test a given capacitive accelerometer. The application of the sensor is vibration monitoring on a mechanical engine in a specific frequency range (from 40 Hz to 400 Hz). The MEMS device has a mass of 8nK g , a mechanical stiffness of 5N /m and a quality factor Q = 2. The capacitiv...

Motivated by a need within the aerospace industry to detect and characterize degradation in the insulation of onboard wires, this thesis reports testing of several extant methods and development of novel capacitive sensors. The work focuses on measuring the electrical parameters resistance and capacitance that are directly related to the material parameters conductivity and permittivity, respec...

We describe a technique for measuring the water vapor supersaturation of normal air over a temperature range of 240&T&0 °C. The measurements use an inexpensive commercial hygrometer which is based on a thin-film capacitive sensor. The time required for the sensor to reach equilibrium was found to increase exponentially with decreasing sensor temperature, exceeding 2 min for T5230 °C; however, t...

Capacitive touch sensing is increasingly used in musical controllers, particularly those based on multi-touch screen interfaces. However, in contrast to the venerable piano-style keyboard, touch screen controllers lack the tactile feedback many performers find crucial. This paper presents an augmentation system for acoustic and electronic keyboards in which multi-touch capacitive sensors are ad...

This paper discusses the design of a contact sensor for use with the Utah-MIT dexterous hand [Jacobsen, et al. 19841. The sensor utilizes an 8 x 8 array of capacitive cells. This paper extends the work presented in Siegel and Garabieta [1986], and the earlier work of Boie [1984]; a more detailed design analysis, modifications to the construction process, and better performance results, are shown.

Small molecule S-nitrosothiols are a class of endogenous chemicals in the body, which have been implicated in a variety of biological functions. However, the labile nature of NO and the limits of current detection assays have made studying these molecules difficult. Here we present a method for detecting trace concentrations of S-nitrosothiols in biological fluids. Capacitive sensors when coupl...

In this work, we present a capacitance-to-voltage converter (CVC) for capacitive accelerometers based on microelectromechanical systems (MEMS). Based on a fully-differential transimpedance amplifier (TIA), it features a 34-dB transimpedance gain control and over one decade programmable bandwidth, from 75 kHz to 1.2 MHz. The TIA is aimed for low-cost low-power capacitive sensor applications. It ...

In this paper, measurement results for a micropower 2MHz CMOS frequency reference circuit fabricated with a ml2 13 M7 M5 M6 M8 :Ml8 M19 0.13 ,um CMOS process are presented. This frequency reference circuit, based on source-coupled CMOS multivibrator, provides M14 m 2 M22 the clock signal for a read-out circuit of a capacitive sensor. In Cm addition to a low power consumption, a good frequency s...

 This article presents an analysis for two related concepts of a capacitive incremental position sensor. In Incremental Capacitance Measurement Mode the periodic change in capacitance is measured to determine the relative displacement between two periodic geometries S1 and S2 with gap-distance of ~ 1 μm. In Constant Capacitance Measurement Mode the distance between S1 and S2 is controlled to k...