Silicon Nanowire Arrays for Thermoelectronic Power Harvesting

Idiana Hamidi

Thermoelectric devices are commonly composed of a bismuth-tellurium compound which is expensive and have limited resource. Alternatively, silicon, a semiconductor may be a prominent material in thermoelectric devices. However, high thermal conductivity in bulk Si affects the thermo-electric efficiency. On the contrary, the nanostructured Si i.e. nanowires can be used in enhancing thermoelectric properties.

A potential difference between two ends, known as Seebeck voltage, Voc, is developed when a semiconductor material is heated from one side and cooled from the other to create a temperature gradient.

Researchers from Process Tomography Research Group & Instrumentation (PROTOM-i), the research arm of UTM Faculty of Electrical Engineering in their research, investigate the performance of Silicon Nanowire Arrays (SiNWAs) and bulk Si material as thermoelectric power.

SiNWAs as an element in power harvesters utilize green technology in which there are solid-state parts that are able to increase the longevity of a power harvesting device, while its non-toxic, emissions-free and noiseless characteristics encourage a healthier environment. Inexpensive and commonly found silicon material, and a simple fabrication technique without any requirement of expensive tools to build SiNWAs power harvesting device promote economic advantages to the manufacturers and end-consumers.

a) Fabricated device with copper sheets attached (left); and close-up FESEM image of SiNWAs (right). b) The thermal image at each layers of the device (i.e. top Cu sheet, Si and bottom Cu sheet).

Development of Radio-Controlled MEMS implantable Drug-Delivery Device with Selective and Controlled-Release Capability using Shape-Memory-Alloy Microactuators

This article describes the development of an out-of-plane shape-memory-alloy microactuator, a shape-memory-polymer drug delivery device, a thermopneumatic micropump, and a selective drug delivery device. These devices are powered and controlled by frequency manipulation of an external magnetic field.

Over the past decade, the technology and applications of drug-delivery devices have gained tremendous interest. However, the ability to implement these devices in portable and implantable applications is still limited. To date, such devices are restricted to the use of bulky magnetic cores or on-board power supplies. These approaches require consideration of several practical issues, such as the device size and complexity as well as feasibility for biomedical applications and multiple-actuator control. Passively actuated actuators offer the opportunity to minimize the size and cost of such systems while maintaining a higher robustness and longevity as compared to actively actuated actuators.