Micro piezoelectric energy harvester
A maintenance-free power source with high energy density for the wireless sensor network is one of the most interesting topics in our group. The wireless sensor network is useful to large scale observation such as structural health monitoring for skyscrapers or power plants, and environment observation of forest, river, or ocean. Therefore, the power source must be harmless with consideration for the environment. Lead-free piezoelectric material is a key to develop such power source. We are developing the micro power generator employing such lead-free materials.
Scanning Thermal Microscopy Probes
A scanning thermal microscope, which will be capable of measuring temperature of a micro and/or nanometer region, is under development. The microscope will measure topography and the temperature distribution at the same time by employing an AFM probe that has an integrated pyroelectric sensor on the apex. It will be possible to measure temperature without contacting the specimen because the temperature is determined by infrared radiation. Furthermore, the method will enable accurate measurement because of the absence of heat transfer due to the mechanical contact.
Micro-scale Control of Fluids by using Surface Acoustic Waves
The general term “surface acoustic wave” represents waves that propagates on the surface of a material, where energy is concentrated. Devices based on surface acoustic waves has a wide variety of applications such as filters, signal processing devices, sensors and linear-motors. We investigate properties of microfluidic devices using surface acoustic waves that can control flow rates, and is capable of mixing two fluids. The microfluidic device we are developing will be able to control the flow rate continuously in a wide range.
Micro energy harvesters based on electrets
In the envisioned “ubiquitous sensor networks”, it is desirable that all the numerous sensor nodes be free from the need for maintenance. Hence one hopes to eliminate the necessity to exchange batteries on a regular basis. The idea of micro-energy harvesting, which is to obtain energy from the environment in the form of light, heat or vibration, attracts much attention recently. We study electret-based micro energy harvesters that uses electrostatic induction to generate power from vibrations in the environment. (An electret is a dielectric that contains permanent electric charge.)
A micro-fabricated ion source
Ion-beams are often employed to fabricate microstructures on the scale of few hundred nanometers to several microns. It is possible to generate an ion beam by applying a high voltage on the order of a few kV to a fine needle that is wet with a liquid metal. We aim at downsizing such an ion source.