Displacement Sensor with Inherent Read-Out Circuit Using Water-Gated Field Effect Transistor (WG-FET)

This paper presents, for the first time, a displacement sensor with inherent read-out circuit using an inverter built with WG-FET that has 16-nm-thick single crystalline silicon film. In WG-FET, electrical double layer (EDL) capacitances are formed at water/silicon and water/top gate interfaces. These two capacitances and the resistance of the de-ionized (DI) water droplet build a first order RC network. Propagation delay of an inverter built with WG-FET depends on this RC constant. When the distance between top gate and silicon film changes, EDL capacitances remain the same, but resistance of the DI-water droplet changes. Accordingly, propagation delay of the inverter changes linearly with this distance. Increasing the distance from 400 µm to 1200 µm changes low-to-high propagation delay tplh of the inverter from 1.08 ms to 1.36 ms and high-to-low propagation delay tphl from 0.48 ms to 0.56 ms, which yields sensitivities of 0.35 µs/µm and 0.1 µs/µm, respectively.

A simple method to experimentally determine the accurate RC-constant in nanosecond timescale transient photocurrent measurements on organic solar cells

Experimentally determine the RC-constant in ns-TPC measurements on OSCs.

Resonant modulation

Devices that offer fast modulation and switching of light waves currently attract widespread research efforts for potential applications in high-speed signal processing. The guided-wave techniques of integrated optics have demonstrated the capability to achieve drive power/bandwidth levels of a few milliwatts per gigahertz modulation bandwidth. Most recently, efforts have been concentrated on electro-optic travellingwave configurations (Alferness et al . 1983; Gee & Thurmond 1983; Cross et al . 1984) to achieve operation at higher frequencies with higher bandwidths than are usually obtainable from lumped-electrode devices, wherein the dominant restriction of the speed of operation is the RC constant associated with electrode charging and discharging. Here, we discuss the potential merits of an alternative approach, which employs resonant optical waveguide cavities.

OXYGEN TENSION MEASUREMENT BY A METHOD OF TIME SELECTION USING THE STATIC PLATINUM ELECTRODE WITH ALTERNATING POTENTIAL

1. The possibility of obtaining sustained and reproducible results in the analysis of dissolved oxygen with simple platinum electrodes by means of the application of a periodic potential pattern was explored over a wide range of frequencies and with a variety of wave forms. 2. Satisfactory results were obtained by the application in the frequency range of 5 to 10 C.P.M. of a square wave consisting of a positive and a negative pulse with interposed shorting periods and observing the current flowing at the end of each successive negative pulse. This was found to be linearly proportional to O2 concentration for a pulse duration of the order of 1 second when the RC constant of the circuit was sufficiently small. 3. An instrument was developed to provide the required wave form and record the terminal currents of the negative pulses. The instrument provides either for recording of current voltage curves (polarograms) or for continuous recording at a fixed voltage of diffusion limited current values. 4. Typical measurements of oxygen uptake with yeast suspensions illustrate the application of the technique to problems requiring frequent determinations during short intervals. 5. Applications of this technique to biological and other problems are indicated with its limitations.