Research Project

Analysis of micropatterned wireless resonant heaters for wireless-control of MEMS thermal actuators

This research study on wireless radiofrequency (RF) power transfer to and heat generation in micropatterned coils for wireless control of thermally-driven microdevices. Inductor-capacitor circuits with the planar spiral coils act as RF receivers as well as frequency sensitive wireless heaters that selectively produce heat when resonated with external RF magnetic fields. Electrical and thermal characterizations are performed using two sets of microfabricated circuits with varying numbers of turns and fill ratios defined in the spiral coils. The measurements in electrical parameters of the circuits, coupling coefficient, power transfer efficiency, and heat generation have been evaluated and parameters show good consistency between them. These tests reveal maximum power transfer efficiency and steady-state temperature of *35 and 99 _C, respectively, for the coil with a fill ratio of 0.55. The reported results will serve as a basis for the design of the wireless heater, which provide a promising path to radiocontrol of thermoresponsive actuators such as shapememory alloys and hydrogels.

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Wireless Implantable Drug Delivery Device Based On Shape Memory Alloy Microactuator

This project propose a novel out-of-plane microactuator based on a bulk-micromachined SMA coil with a built-in heater that is controlled wirelessly using RF magnetic fields. The out-of-plane SMA coil will be microfabricated through a planar process and self-assembled by locally controlled bending of the coil structure. The SMA coil acts as both a resonant& heater circuit, which receives RF power wirelessly for heat generation, an a vertical actuator structure. This monolithic approach is aimed to reduce the overall size of the actuator and heat loss associated with the hybrid device, while eliminating the need for bonding and assembly processes for SMA integrat ion. Direct wireless heating of the SMA coil is expected to improve temporal response and reduce the temperature gradient of the actuator.

MEMS Thermopile Wearable Power Harvesting Device

In these days, more focuses are directed to the design of micro-power generators harnessing MEMS technology. These indirectly lead to the invention of alternative self-powered harvesters that are smaller in size and implantable so as to augment or surrogate the conventional large scale energy transducers, and to reduce the usage of main power supplier. Here, the main inspirations are to add simplicity and easiness into the daily life, less cost, and respecting the nature of ecosystem. Subsequently, implying ambient energies and radiations can be a great alternative as they are ecological friendly and renewable. Also in that manner, the life durations and capabilities of such energy scavenging systems can be upgraded. Similarly, small scaled thermoelectric power plants are very useful for easy powering or charging of mobile electronics even at remote areas without expecting a main power supplies. So, the systems are commonly applied as wireless sensor networks. Besides, such self-powered devices also encompass several extra benefits that may attract more attentions towards their systems viability. Micro-thermoelectric generator directly converts thermal energy into potential differences. It is a low cost generator with reliable energy source and has no moving blocks thereby, easily scalable. Moreover, it can be used to recycle wasted heat energy, so it also endows to a healthier atmosphere. In this project, several important elements such as, flexibility of the thermo-electric power harvesting device, portability, low cost factors, and best possible thermo-electric materials that provides highest output power will be analyzed.

Wireless flow-control method for centrifugal microfluidic application

This project demonstrates the flow controlled functionality using RF wireless mechanism for lab on chip (LOC) device. This approach aims to control the flow switching sequence for centrifugal microfluidic application during spinning process, where a conventional valving principle is hardly to be implemented. In addition, the heat induced from the RF heating can be utilised as an actuation mechanism to eject a controlled amount of dosage to the targeted area, which further eliminates the requirement of batteries and active circuitry in micropump application. 

Integration of Shape-Memory-Alloy Actuator and Its Application as Micromanipulator

Bulk shape-memory-alloy actuators have great potential to be used in various microdevices. Previous studies show that this material is very attractive due to its very large force, high mechanical robustness with a simple structure and biocompatibility. This research present a novel shape memory alloy micromanipulator through applying an integration of multiple shape memory alloy microactuators. The micromanipulator will be developed using monolithic approach. Due to the challenges exist in developing the integration and the monolithic approaches into micro-electro-mechanical systems (MEMS) fabrication, the success of bulk shape memory alloy in MEMS is rather limited today. The successful outcomes of this research are expected to promote advances in these device technologies in biomedical fields and beyond. This report discusses the important measures that are necessary to develop the shape memory alloy micromanipulator, and then reviews on the challenges and status of current strategies.

Frequency-Controlled Wireless Piezoelectric Microactuator for Microfluidic Application

Recently, piezoelectric-driven micro-sized pumps have been developed for applications in microfluidics, biomedical and biochemistry diagnostics, fuel cell systems, drug delivery, and high-power electronics cooling, etc. This study describes a frequency-controlled wireless piezoelectric microactuator for microfluidic applications for highly precise constant flow rate. The piezoelectric microactuator used, Murata®PAZ-10-0080, is modeled based on Bouc-Wen model, where the parameters are estimated using Particle Swarm Optimization (PSO) and then simulated via MATLAB Simulink. Then, the results are verified with experiments. The microfluidic device is designed using Finite Element Modeling (FEM) via COMSOL Multiphysics. An LC circuit that is connected to the piezoelectric microactuator is then designed via COMSOL Multiphysics. Then, the whole structure of the microfluidic device is fabricated based on Microelectromechanical systems (MEMS) fabrication standards. Lastly, the performance of the device is characterized and enhanced using experiments.