Optical panel with full multitouch using patterned indium tin oxide.

This study proposes an optical panel with full multitouch using the patterned indium tin oxide (ITO) and an algorithm matrix to avoid ghost points. The patterned ITOs include the virtual high and low impedances. The algorithm matrix with two configurations of equivalent circuits for array scanning is derived using the voltage divider rule. The fabrication process of the multitouch panel is carried out using microelectromechanical systems technology. The optical characteristics of the multitouch panel in the UV, visible, and IR regions are measured using photometric analysis. The multitouch panel, containing sensing pixels of 30×30 arrays, has a pixel size of 2×2 mm2 and a pitch distance of 2 mm. The average values of high and low impedances are 53.23 and 9.3 k Ω, respectively. The maximum transmittance is about 74.2% at the wavelength of 692 nm. The multitouch panel based on high and low impedance patterns has been specifically designed to offer good adjacent touch resolution and sensitivity for reality multitouch applications. In addition, the patterned design and the algorithm matrix provide unlimited multitouch points and avoid ghost points.

Interface dynamics and mechanisms of nanoindented alkanethiol self-assembled monolayers using molecular simulations.

The interface and nanoindentation mechanisms of alkanethiol self-assembled monolayers (SAMs) chemisorbed on a gold surface are investigated using molecular dynamics simulation. The mechanisms include the nanoindentation depths, the workpiece temperatures, the numbers of SAM layers, the length of united-atoms per chain, and the shapes of the indenters. The simulation results show that the disorder and the plastic mobility of SAM chains increased with increasing indentation depth. The relaxation force and the plastic energy almost linearly increased with increasing indentation depth. The disorder region after indentation at high temperature is larger than that at low temperature. The adhesive force shows a dependence on temperature during indentation. The potential energy decreases with increasing number of SAM layers. The structural morphologies of the SAMs were not affected at the third layers for SAM film with four layers. The maximum load quickly decreases for film with two SAM layers. The structures of the SAM can be easily tilted and bent when the united-atoms per chain length is long. The SAM atoms become more disorderly and the elastic recovery is smaller when the SAM length of the united-atoms per chain is long after indentation.

Optical properties of one-dimensional photonic crystal with a twisted-nematic defect layer.

Spectral properties of an electrically tunable one-dimensional photonic crystal infiltrated with a twisted-nematic liquid crystal (PC/TN) are investigated. Two mesogenic materials with dissimilar optical anisotropies are examined for constituting the central defect layer. With the TN alignment of the defect layer embedded in the dielectric multilayers, the defect modes not only shift with the applied voltage but also switch between two major modes when the linear polarization angle of the incident light is altered. The superposition of the mixed-mode TN (MTN) and the photonic bandgap brings out a tremendous undulation in all range of the transmission spectrum. The defect modes falling at the centers of the MTN spectral humps are allowed to intensely transmit while the others are suppressed. As a result, we propose a monochromatic selector constructed by such a PC/MTN device with electrical tunability.

Molecular dynamics on interface and nanoscratch mechanisms of alkanethiol self-assembled monolayers.

The interface dynamics and nanoscratched mechanisms of alkanethiol self-assembled monolayers (SAM) chemisorbed on a gold surface are investigated using molecular dynamics simulation. The characteristic mechanisms mainly include the nanoscratched depths, the workpiece temperatures, the scratched speed, the SAM chain lengths, and the shapes of the indenters. The simulation results show that the disorder and the plastic mobility of SAM structures increased with increasing nanoscratched depth. The scratched forces, the potential energy, the friction force, and the friction coefficient increased with increasing scratched depth. The larger scratched depth required a larger force to overcome the resistance, which leads to the increases in the friction force. The variations of the scratched forces and the friction forces after scratching at various temperatures are very similar. An increase in the scratched force, friction force, and friction coefficient with increasing scratched speed is observed. The scratched shape after scratching is clearer for a longer SAM chain. The SAM structures are easily tilted and bent when the chain length is longer. The reaction forces after scratching using a spherical indenter are higher than those after scratching using a Vickers indenter.

Flexible electronics sensors for tactile multiscanning.

Flexible electronics sensors are designed and fabricated for tactile multiscanning and large area applications. The algorithm matrix is derived for multiscanning switch of tactile sensing. The thixotropy materials, bump, and resistance material are printed on the polyimide substrate. A gap between the top electrode and the resistance layers provides a buffer distance to increase the radius of curvature for large bending. Experiment results show that a flexible electronics sensor with a printed a resistance layer and an algorithm matrix performed the multiscanning functions. The membrane without a bump had a delay time of about 0.2 s at the transient response and took a longer time to reach the stable state after a force is applied. For printing thick structures on the flexible substrates, diffusion effects, and dimensional shrinkages can be reduced by using a thixotropy material with a high viscosity. The probability distribution density of the printed resistance values, a thickness of about 23.2 microm, at two standard deviations from the mean values is about 81.2%. Feasibility studies show that screen printing is appropriate for large area applications and is a low-cost technology for fabricating flexible electronics sensors.

Flexible electronics sensors for tactile multi-touching.

Flexible electronics sensors for tactile applications in multi-touch sensing and large scale manufacturing were designed and fabricated. The sensors are based on polyimide substrates, with thixotropy materials used to print organic resistances and a bump on the top polyimide layer. The gap between the bottom electrode layer and the resistance layer provides a buffer distance to reduce erroneous contact during large bending. Experimental results show that the top membrane with a bump protrusion and a resistance layer had a large deflection and a quick sensitive response. The bump and resistance layer provided a concentrated von Mises stress force and inertial force on the top membrane center. When the top membrane had no bump, it had a transient response delay time and took longer to reach steady-state. For printing thick structures of flexible electronics sensors, diffusion effects and dimensional shrinkages can be improved by using a paste material with a high viscosity. Linear algorithm matrixes with Gaussian elimination and control system scanning were used for multi-touch detection. Flexible electronics sensors were printed with a resistance thickness of about 32 µm and a bump thickness of about 0.2 mm. Feasibility studies show that printing technology is appropriate for large scale manufacturing, producing sensors at a low cost.

Phase Detection of the Two-port FPW Sensor for Biosensing.

In this study, we provided a comprehensive methodology for designing and integrating miniature system in the biosensor application. In general, the network analyzer is commonly used for acoustic wave sensor measurement. However, it is remarkably inconvenient for portable use. Therefore, we presented a readout concept, which was focused on the miniaturization of the flexural plate wave (FPW) sensor system by integrating phase detection circuit. The miniature system includes a Wien-Bridge oscillator, a voltage following, a FPW device, a phase-locked loop, a phase detector, a MCU, and a LCM display. This work succeeded in integrating all the subsystems. And the core technology of the system is the phase detection function. The results showed the phase shift resolution is 10 mV/1°.

Using Pt Dopant and Sol Gel Technology for Sensitivity Enhancement of TiO2/SnO2Humidity Sensors.

The sensitivity of the humidity sensor based on hybrid thin films of nanostructure TiO2/SnO2with Pt dopant was successfully increased. The humidity-sensitive materials, TiO2/SnO3, were prepared by sol gel technology. The microstructure of the sensing film after calcination was investigated by the Field Emission gun Scanning Electron Microscopy (FESEM) and revealed that the metal oxide hybrid had about 10 nm grain size. For studying the effect of Pt dopant on the humidity-sensitive responses, 1 ml to 10 ml of Pt standard solution was added into the colloidal solution. To compare the humidity sensor of Pt dopant with that of no Pt dopant, operational frequencies and electrode spacing were set under the relative humidity from 30 % to 95 % at the ambient temperature of 22 °C. We demonstrated that adding Pt dopant remarkably enhanced the sensitivity of TiO2/SnO2humidity sensor, and further decreased the TiO2/SnO2 resistance, which was 3.3 times lower than that without Pt dopant at the high humidity.