The fingerprint recognition has been widely used for biometrics in mobile devices. Existing fingerprint sensors have already been commercialized in the field of mobile devices using primarily Si-based technologies. Recently, mutual-capacitive fingerprint sensors have been developed to lower production costs and expand the range of application using thin-film technologies. However, since the mutual-capacitive method detects the change of mutual capacitance, it has high ratio of parasitic capacitance to ridge-to-valley capacitance, resulting in low sensitivity, compared to the self-capacitive method. In order to demonstrate the self-capacitive fingerprint sensor, a switching device such as a transistor should be integrated in each pixel, which reduces a complexity of electrode configuration and sensing circuits. The oxide thin-film transistor (TFT) can be a good candidate as a switching device for the self-capacitive fingerprint sensor. In this work, we report a systematic approach for self-capacitive fingerprint sensor integrating Al-InSnZnO TFTs with field-effect mobility higher than 30 cm 2 /Vs, which enable isolation between pixels, by employing industry-friendly process methods. The fingerprint sensors are designed to reduce parasitic resistance and capacitance in terms of the entire system. The excellent uniformity and low leakage current (<10 −12 ) of the oxide TFTs allow successful capture of a fingerprint image.

Dyeing of a poly(vinyl alcohol) (PVA) film with a high degree hydrolysis (>98%) using Direct Black 22, a dichroic organic dye, was investigated under various conditions (dye concentration, salt (Na 2 SO 4 ) concentration, and temperature). This process could correctly be analyzed using the Freundlich isotherm (C film =K F C soln 1/n ) based on the pore model. The Freundlich exponent 1/n appeared to be constant over a broad range of salt concentrations, but the Freundlich constant K F assumed the maximum value for [Na 2 SO 4 ]=~0.010 M. However, this value was 10 times greater than that under the no-salt conditions. Analysis of the adsorption kinetics revealed that only the early stage of dyeing was followed second-order, with an activation energy of 50.2 kJ/mol. However, gradual deviation from the second-order occurred with an increase in the dyeing time. These results indicated that the surfaces of the inner pores in the PVA film are dyed through multilayer adsorption, which is accompanied by complicated kinetics.Keywords: poly(vinyl alcohol), dichroic dye, dyeing, Freundlich's isotherm, pore model, the second-order kinetics

In the system of poly(vinyl alcohol) (PVA)/dimethyl sulfoxide, the refractive index of polymer was very well matched to that of solvent and thus its scattered intensity could be minimized. After adding small amount of polystyrene latex particle (nominal diameter 200 nm), diffusion behavior of only probe particle was investigated against the concentration of polymer matrix by means of dynamic light scattering. The polymer concentration dependence of its reduced diffusion coefficient was able to be analysed with the stretched exponential function of the reduced concentration C[η]. In very dilute concentration regime, the depletion layer kept constant but at the early semi-dilute regime of 1≤C[η]≤2.5, the concentration-dependent exponent of depletion layer δ was appeared to be -0.8 which was very close to theoretical one of -0.85. However it was also observed at the higher concentration that its layer thickness decreased more abruptly than theoretical expectation and this phenomenon was ascribed to Oosawa type attractive interaction between adjacent latex particles.