Field-Effect Transistor Arrays

Liquid-cr57Stal displays normally employ a matrix of amorphous silicon TFTs to control the voltage applied to the individual pbcels. In order to drive an active-matrix addressed flat-panel LCD, it is necessary to make contact to each of the row and 

---

I. Freund, and B. Wolf, Non-invasive measurement of cell membrane associated proton gradients by ion-sensitive field effect transistor arrays for microphysiological and bioelectronical applications. Biosens. Bioelectron. 15, 117-124 (2000). 

Offenhausser A, Sprossler C, Matsuzawa M, Knoll W (1997) Field-effect transistor array for monitoring electrical activity from mammalian neurons in culture. Biosens Bioelectr 12 819-826... 

The principles of field effect devices with special regard to chemical sensing will be briefly described in the next section. It will be demonstrated how such devices can be used in sensor arrays eventually together with other types of gas sensors to make electronic noses for the identification, classification and analysis of gas mixtures (or odours) [5-7]. A truly microanalytical system, an "olfactory camera" based on a field effect transistor array is also suggested. 

Figure 18. Diagrammatic structure of an active matrix structure using a simple field effect transistor array as the active element.

Although astronomy is accustomed to the detection of a few photons per pixel, the electric charge of a few electrons is extremely small. A critical part of the design of a focal plane array is the amplifier which converts the small amount of charge in each pixel into a signal that can be transmitted off the detector. The amplifier in an optical or infrared detectors is typically a field effect transistor (FET), a solid state structure which allows a very small amount... 

See also Field effect transistors (FETs) Heterojunction insulated gate FETs (HIGFETs), 22 164. See also Field effect transistors (FETs) Heterojunction photodiode arrays,... 

Although the development of field-effect transistors (FETs) has already reached a high level of perfection in crystalline silicon (c-Si), a-Si H offers the advantage that very large arrays of a-Si H FETs are feasible. Hence, even if their performance level is much lower than that of c-Si FETs, there are still many applications where their characteristics may be adequate. In Chapter 6, LeComber and Spear review the design, fabrication, and performance of a-Si H FETs. They point out the need for good ohmic connec-... 

A schematic view of a microdielectrometer sensor is shown in Fig. 8 and illustrates the electrode array, the field-effect transistors and a silicon diode temperature indicator 15) which functions as a moderate accuracy ( 2 °C) thermometer between room temperature and 250 °C. The sensor is used either by placing a small sample of resin over the electrodes, or by embedding the sensor in a reaction vessel or laminate. Since all dielectric and conductivity properties are temperature dependent, the ability to make a temperature measurement at the same point as the dielectric measurement is a useful feature of this technique. 

Research on large area electronic arrays of a-Si H devices started a few years later after the first field effect transistors were reported (Snell et al. 1981). These devices take advantage of the capability to deposit and process a-Si H over large areas. Applications include liquid crystal displays, optical scanners and radiation imagers. Present devices contain up to 10 individual elements and are presently used in handheld televisions and FAX machines. 

A bilayer structure usually consists of two different films deposited on a substrate, one overlying the other. A typical system consists of a Pt substrate with an electro-deposited film of poly-[Ru(vbpy)3 ] on which a film of poly-[Os(bpy)2(vbpy)2" ] is elec-trodeposited (25). Another type of sandwich structure involves a pair of closely spaced electrodes such as in an electrode array (26), bridged by a polymer film. Alternatively, a different polymer can be deposited on each electrode of an array pair to form a bilayerlike arrangement having a junction where the films meet. Three-electrode devices of this type can produce a structure functionally equivalent to a field effect transistor (FET) (27). 

Living cells acting as parts of bioelectronic hybrid systems offer intriguing avenues for the development of biosensors, bioinformatics and implantable devices for the restoration of function. A crucial issue is the functional coupling of the output signal from the cell system to a micro-electronic or opto-electronic transducer unit. Tlie coupling of excitable cells with an array of field-effect transistors (FETs) integrated into the bottom of a cell culture dish allows the measurement of action potentials. 

---