Wireless energizing system for an automated implantable sensor.

The wireless drive of an automated implantable electronic sensor has been explored for health monitoring applications. The proposed system comprises of an automated biomedical sensing system which is energized through resonant inductive coupling. The implantable sensor unit is able to monitor the body temperature parameter and sends back the corresponding telemetry data wirelessly to the data recoding unit. It has been observed that the wireless power delivery system is capable of energizing the automated biomedical implantable electronic sensor placed over a distance of 3 cm from the power transmitter with an energy transfer efficiency of 26% at the operating resonant frequency of 562 kHz. This proposed method ensures real-time monitoring of different human body temperatures around the clock. The monitored temperature data have been compared with a calibrated temperature measurement system to ascertain the accuracy of the proposed system. The investigated technique can also be useful for monitoring other body parameters such as blood pressure, bladder pressure, and physiological signals of the patient in vivo using various implantable sensors.

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption.

Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%-95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

Droplets merging through wireless ultrasonic actuation.

A new technique of droplets merging through wireless ultrasonic actuation has been proposed and experimentally investigated in this work. The proposed method is based on the principle of resonant inductive coupling and piezoelectric resonance. When a mechanical vibration is excited in a piezoelectric plate, the ultrasonic vibration transmitted to the droplets placed on its surface and induces merging. It has been observed that the merging rate of water droplets depends on the operating frequency, mechanical vibration of piezoelectric plate, separation distance between the droplets, and volume of droplets. The investigated technique of droplets merging through piezoelectric actuation is quite useful for microfluidics, chemical and biomedical engineering applications.

An ultrasonic contact-type position restoration mechanism.

An ultrasonic contact-type position restoration mechanism is proposed and investigated in this paper. In the mechanism, two driving points of an ultrasonic vibrator, excited by an AC voltage, produces a restoring force on a slider so that the slider can be pushed back to its equilibrium after it is perturbed away from its equilibrium. The restoring force is generated by the unbalance of ultrasonic frictional driving forces on the slider, which is caused by a pressure difference on the two driving points. A prototype of this mechanism is fabricated, and the effects of the driving voltage, preload between the slider and vibrator, and slider's size on the restoring characteristics are experimentally measured and analyzed.

Manipulations of silver nanowires in a droplet on a low-frequency ultrasonic stage.

In this work, we report the use of a low-frequency circular ultrasonic stage to form a circular spot of silver nanowires (AgNWs) at the stage center and to radially align AgNWs on the stage surface. The manipulations are implemented within an AgNW suspension droplet at the center of the ultrasonic stage. The ultrasonic stage (50.8 mm diameter, 3.5 mm thick) operates at a flexural vibration mode symmetric about its center and has a vibration peak at the center. The AgNW suspension is formed of deionized water with AgNWs dispersed in it. The operating frequency of the ultrasonic stage is 21.3 kHz; the AgNWs have diameter of 100 nm and length of approximately 30 µm. When the ultrasonic stage vibrates properly, AgNWs on the substrate surface in the droplet may move to the stage center and form a spot or rotate to the radial direction and align radially. The spot diameter and thickness are several hundred micrometers and several micrometers, respectively. The rotation speed of a single AgNW can be up to 31°/min when the vibration velocity of the stage center is 42 mm/s (0-p) for a 40-µL droplet. After the droplet dries out by natural evaporation without ultrasound, the spot and radial alignment have little change in the size and pattern. Principle analyses show that the spot formation and radial alignment of AgNWs are caused by the acoustic streaming in the radial direction in the droplet.