Zhiyu Wen

A Laser-micromachined Vibrational to Electrical Power Transducer for Wireless Sensing Systems

This paper presents the development of a vibration-induced power generator with total volume of ∼cm3 which uses laser-micromachined springs to convert mechanical energy into useful electrical power by Faraday’s Law of Induction. The goal of this project is to create a minimally sized electric power generator capable of producing enough voltage to drive low-power ICs and/or micro sensors for applications where ambient mechanical vibrations are present. Thus far, we have fabricated generators with total volume of 1cm3 that are capable of producing up to 4.4V peak-to-peak, which have a maximum rms power of ∼680µW with loading resistance of 1500Ω. The mechanical vibration required to generate this electrical energy has frequencies ranging from 60 to 110Hz with ∼200µm amplitude. We have demonstrated that this generator can drive an IR transmitter to send 140ms pulse trains every minute, or a 914.8MHz FM wireless temperature sensing system.

A Preliminary Study of the Noninvasive Remote Control System for Rat Bio-Robot

A system is described here that can noninvasively control the navigation of freely behaving rat via ultrasonic, epidermal and LED photic stimulators on the back. The system receives commands from a remote host computer to deliver specified electrical stimulations to the hearing, pain and visual senses of the rat respectively. The results demonstrate that the three stimuli work in groups for the rat navigation. We can control the rat to proceed and make right and left turns with great efficiency. This experiment verified that the rat was able to reach a setting destination in the way of cable with the help of a person through the appropriate coordination of the three stimulators. The telemetry video camera mounted on the head of the rat also achieved distant image acquisition and helped to adjust its navigation path over a distance of 300 m. In a word, the non-invasive motion control navigation system is a good, stable and reliable bio-robot.

An Intelligent Electronic Capsule System for Automated Detection of Gastrointestinal Bleeding

In clinical practice, examination of the hemorrhagic spot (HS) remains difficult. In this paper, we describe a remote controlled capsule (RCC) micro-system with an automated, color-based sensor to identify and localize the HS of the gastrointestinal (GI) tract. In vitro testing of the detecting sensor demonstrated that it was capable of discriminating mimetic intestinal fluid (MIF) with and without the hemoglobin (Hb) when the concentration of Hb in MIF was above 0.05 g/ml. Therefore, this RCC system is able to detect the relatively accurate location of the HS in the GI tract.

Optimization of Q factor in spiral inductor on silicon

In this paper, analyzing the Q factor of the spiral inductor is done by computer simulation, the results showed that the series resistance R/sub s/ dominates the Q factor of the spiral inductor, and that increasing the substrate silicon resistance is beneficial to increasing the Q factor and decreasing the substrate noise. To increase the Q factor of the spiral inductor, the experiments of decreasing via contact resistance and etching away the substrate silicon under the spiral inductor are done. The compatibility of the 3-dimensional bulk process with the planar IC process has been solved. Using the novel method, the inductor with high Q factor of 8.4 and low series resistance of 3 /spl Omega/ is obtained, and substrate noise is reduced. This method can be used effectively in the design and manufacturing of high performance RF-ICs.

Polysilicon micromachined switch

LPCVD SiO2 and polysilicon being used as sacrificial layer and cantilever respectively, a polysilicon micromachined RF switch has been fabricated. In the process the stress of polysilicon is released to prevent polysilicon membrane from bending. The switch offers the potential for building a new fully monolithic integrated RF MEMS for radar and communications applications.