The effects of an O2 plasma-treated SiNX-based insulator on the interfacial property and the device performances of amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) were investigated. We tried to improve the interfacial characteristics by reducing the trap density between the SiNX gate insulator and a-IGZO channel by the O2 plasma treatment. The plasma treated-device performances were remarkably improved. The drastic improvements obtained for the O2 plasma-treated a-IGZO TFTs included excellent bias stability as well as a high field effect mobility (μFE) of 19.4 cm2/V s, an on/off current (ION/IOFF) of 108, and a subthreshold value (S) of 0.5 V/decade.

A new type of three-dimensional (3D) Frequency Selective Surfaces (FSS) applied to passive sensing in Structural Health Monitoring (SHM) is presented. Such passive FSS sensors are proposed as an alternative to conventional sensors to eliminate the need of DC/AC power. Moreover, these FSSs are modified in a 3D form to feature enhanced performance compared to conventional FSSs and sensors. More specifically, the proposed 3D FSS is able to control its sensitivity |S 21 | in either TE or TM incident waves. In this project, incident angle characteristics are evaluated for SHM applications to obtain angular responses of up to 80 degrees. The resonant behavior of the TE-incident wave is shown to be sensitive towards the incident angle and is suitable to be used for monitoring any building tilting and damage. This is due to the significant 3D length changes of the conductor elements. Meanwhile, the TM-incident wave is found to be insensitive towards the incident angle.

This paper presents the design, test and improvement of a newly developed piezoelectric torsional actuator which generates large angular displacement using piezoceramics and a torsion bar. Because the proposed piezoelectric torsional actuator can generate torsional displacement, directly invoking the shear mode of the piezoelectric material, no complicated additional mechanism is needed. The electrodes are formed from a cylindrical piezoceramic poled along the axial direction and divided into six segments that are arranged radially and bonded to each other in opposite poling directions with conductive adhesive. The key to designing such an actuator is to match the torsional resonant frequency of the actuator with the excitation frequency. Finite element analysis for the piezoelectric actuator is performed to find the torsional resonant mode; an experimental investigation in terms of electrical impedance and torsional displacement measurement was conducted to verify the mode. As a result a maximum angular displacement of 0.18° was measured. To magnify the torsional displacement, a torsion bar was attached on top of the actuator. Thus, the torsional displacement was magnified by a factor of three. A resonance decrease due to the added mass of the torsion bar was observed and a theoretical investigation was performed using a two degrees of freedom lumped model.

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