Resistive touchscreen

About: Resistive touchscreen is a research topic. Over the lifetime, 13366 publications have been published within this topic receiving 157870 citations.

Damping of structural vibrations with piezoelectric materials and passive electrical networks

Abstract: The possibility of dissipating mechanical energy with piezoelectric material shunted with passive electrical circuits is investigated. The effective mechanical impedance for the piezoelectric element shunted by an arbitrary circuit is derived. The shunted piezoelectric is shown to possess frequency dependent stiffness and loss factor which are also dependent on the shunting circuit. The generally shunted model is specialized for two shunting circuits: the case of a resistor alone and that of a resistor and inductor. For resistive shunting, the material properties exhibit frequency dependence similar to viscoelastic materials, but are much stiffer and more independent of temperature. Shunting with a resistor and inductor introduces an electrical resonance, which can be optimally tuned to structural resonances in a manner analogous to a mechanical vibration arsorber. Techniques for analyzing systems which incorporate these shunting cases are presented and applied to a cantilevered beam experiment. The experimental results for both the resistive and resonant shunting circuits validate the shunted piezoelectric damping models.

An ultra-sensitive resistive pressure sensor based on hollow-sphere microstructure induced elasticity in conducting polymer film

Abstract: Pressure sensing is an important function of electronic skin devices. The development of pressure sensors that can mimic and surpass the subtle pressure sensing properties of natural skin requires the rational design of materials and devices. Here we present an ultra-sensitive resistive pressure sensor based on an elastic, microstructured conducting polymer thin film. The elastic microstructured film is prepared from a polypyrrole hydrogel using a multiphase reaction that produced a hollow-sphere microstructure that endows polypyrrole with structure-derived elasticity and a low effective elastic modulus. The contact area between the microstructured thin film and the electrodes increases with the application of pressure, enabling the device to detect low pressures with ultra-high sensitivity. Our pressure sensor based on an elastic microstructured thin film enables the detection of pressures of less than 1Pa and exhibits a short response time, good reproducibility, excellent cycling stability and temperature-stable sensing.

Microchannel plate detectors

Abstract: A microchannel plate (MCP) is an array of 104-107 miniature electron multipliers oriented parallel to one another (fig. 1); typical channel diameters are in the range 10-100 μm and have length to diameter ratios (α) between 40 and 100. Channel axes are typically normal to, or biased at a small angle (~8°) to the MCP input surface. The channel matrix is usually fabricated from a lead glass, treated in such a way as to optimize the secondary emission characteristics of each channel and to render the channel walls semiconducting so as to allow charge replenishment from an external voltage source. Thus each channel can be considered to be a continuous dynode structure which acts as its own dynode resistor chain. Parallel electrical contact to each channel is provided by the deposition of a metallic coating, usually Nichrome or Inconel, on the front and rear surfaces of the MCP, which then serve as input and output electrodes, respectively. The total resistance between electrodes is on the order of 10 Ω Such microchannel plates, used singly or in a cascade, allow electron multiplication factors of 10-10 coupled with ultra-high time resolution (< 100 ps) and spatial resolution limited only by the channel dimensions and spacings; 12 μm diameter channels with 15 μm center-to-center spacings are typical. Originally developed as an amplification element for image intensification devices, MCPs have direct sensitivity to charged particles and energetic photons which has extended their usefulness to such diverse fields as X-ray) and E.U.V.) astronomy, e-beam fusion studies) and of course, nuclear science, where to date most applications have capitalized on the superior MCP time resolution characteristics). The MCP is the result of a fortuitous convergence of technologies. The continuous dynode electron multiplier was suggested by Farnsworth) in 1930. Actual implementation, however, was delayed until the 1960s when experimental work by Oschepkov et al.) from the USSR, Goodrich and Wiley) at the Bendix Research Laboratories in the USA, and Adams and Manley) at the Mullard Research Laboratories in the U.K. was described in the scientific literature. These developments relied heavily on a wealth of information on secondary electron emission) and earlier work on the technique of producing resistive surfaces in lead glasses by high temperature reduction (250-450 °C) in a hydrogen atmosphere. Finally, since most of the electrical performance characteristics of channel multipliers are not a function of channel length, l, or channel diameter, d, separately, but only a function of the ratio l/d =α, an almost arbitrary size reduction is possible. Such size reduction may be achieved by glass fiber drawing techniques which form the basis of fiber op tic device fabrication). In addition to a significant dimensional reduction resulting from these methods, a logarithmic compression of repetitive manufacturing steps is also possible, i.e., one can achieve a structure with ~10 holes requiring ~2 x 10 fiber alignment steps by a draw/multidraw technique. Prior to the application of reliable fiber drawing techniques, however, the first operational MCPs were

Electrosurgical jaw structure for controlled energy delivery

Abstract: A working end of a surgical instrument that carries first and second jaws for delivering energy to tissue. In a preferred embodiment, at least one jaw of the working end defines a tissue-engagement plane that contacts the targeted tissue. The cross-section of the engagement plane reveals that it defines a surface conductive portion that overlies a variably resistive matrix of a temperature-sensitive resistive material or a pressure-sensitive resistive material. An interior of the jaw carries a conductive material or electrode that is coupled to an Rf source and controller. In an exemplary embodiment, the variably resistive matrix can comprise a positive temperature coefficient (PTC) material, such as a ceramic, that is engineered to exhibit a dramatically increasing resistance (i.e., several orders of magnitude) above a specific temperature of the material. In use, the engagement plane will apply active Rf energy to captured tissue until the point in time that the variably resistive matrix is heated to its selected switching range. Thereafter, current flow from the conductive electrode through the engagement surface will be terminated due to the exponential increase in the resistance of variably resistive matrix to provide instant and automatic reduction of Rf energy application. Further, the variably resistive matrix can effectively function as a resistive electrode to thereafter conduct thermal energy to the engaged tissue volume. Thus, the jaw structure can automatically modulate the application of energy to tissue between active Rf heating and passive conductive heating of captured tissue to maintain a target temperature level.

Highly Stretchable Resistive Pressure Sensors Using a Conductive Elastomeric Composite on a Micropyramid Array

Abstract: A stretchable resistive pressure sensor is achieved by coating a compressible substrate with a highly stretchable electrode. The substrate contains an array of microscale pyramidal features, and the electrode comprises a polymer composite. When the pressure-induced geometrical change experienced by the electrode is maximized at 40% elongation, a sensitivity of 10.3 kPa(-1) is achieved.