Jong Yeon Park

Fabrication of ionic-polymer-metal-composite (IPMC) micropump using a commercial Nafion

This paper describes the fabrication and characteristics of an ionic polymer-metal composite (IPMC) membrane-shaped micro-actuator and its application to the fabrication of a micro-pump. After fabricating two 8mm×8mm IPMC membrane-shaped actuators using a Nafion film, their displacements were measured. The fabricated IPMC membrane-shaped micro-actuators showed displacement of 14~27μ at the applied voltage ranging from 4VP-P to 10VP-P at 0.5Hz. Displacement of the IPMC actuator fabricated with a commercially available Nafion is large enough to make the IPMC actuator a membrane-shaped micro-actuator for fabricating an IPMC micro-pump. IPMC micro-pump was fabricated by assembling IPMC membrane-shaped micro-actuator and PDMS(polydimethylsiloxane) micro-channel together. PDMS micro-channel was designed to have nozzle/diffuser structures which make the fluids flow from inlet to outlet when the IPMC membrane-shaped micro-actuator is deflected up and down by the applied voltages. The measured flow rate of the fabricated IPMC micro-pump was about 9.9μℓ/min at 0.5Hz when the input voltage and duty ratio were 8V P-P and 50%, respectively. The test results illustrate that the fabricated IPMC micro-pump is suitable for pumping fluid through micro-channel on a PDMS substrate. Mechanical performances of beam-shaped and bridge-shaped conductive polymer actuator in aqueous solution and in solid electrolyte have been measured and analyzed. The optimum thickness of polypyrrole for the best bending performance is about 17-19 μm which has been polymerized at the current density of 5.4 μA/mm2 for 120 minutes. For the application of conductive polymer actuator to a micropump, silicon bulk micromachining process has been combined.

Feed-Horn Antenna for Enhanced Uncooled Infrared Sensor Using Novel UV Lithography, Plastic Micromachining and Mesh Structure Bonding

In this paper, we report a uncooled infrared sensor coupled with a 3-dimensional (3D) feed-horn shape micro-electro-mechanical system (MEMS) antenna using novel UV lithography technique for fabricating a 3D feed-horn-shaped mold array, obtaining parallel light using a mirror-reflected parallel-beam illuminator (MRPBI) system and plastic micromaching. The microassembly of infrared detector and 3D feed-horn-shaped antenna arrays is difficult using the conventional MEMS bonding process. To overcome limitation, the proposed novel 3D MEMS bonding technique is mesh structure bonding (MSB) using microchannels with micromolding in capillaries by polydimethylsiloxane (PDMS). The feasibility of fabricating both a 3D feed-horn MEMS antenna and a mold array was demonstrated. As a result, it seems possible to use a 3D feed-horn-shaped MEMS antenna to improve uncooled infrared sensor performance and applications to fabricate MEMS device.

3D MEMS antenna for IR sensor using novel UV-lithography, plastic micromachining and mesh structure bonding technique

This paper describes the novel UV-lithography technique for fabrication of 3D feed horn mold structure array using implementation of mirror reflected parallel beam illuminator (MRPBI) system, fabrication of 3D feed horn MEMS antennas plate using plastic micromachining (PMM) by polydimethylsiloxane (PDMS) and the 3D MEMS antenna array are assembled using novel 3D MEMS bonding technique by mesh structure bonding (MSB) method.

Array type dissolved oxygen sensor and measurement system for simultaneous measurement of cellular respiration level

This paper describes a miniaturized oxygen sensor array integrated with heaters and temperature sensors and a LabVIEW-based measurement system which exactly can measure a cellular respiration level in a solution containing cells simultaneously. The designed oxygen sensor consists of Clark-type sensors, heaters, and temperature sensors of 2 × 3 array type on the substrate. 18µm PDMS was used for a permeable membrane of Clark-type sensor. The 90% response time was about 10 sec from full-oxygen (air-saturated) state to zero-oxygen (0.1M Na2SO3) state. The fabricated sensor showed good reproducibility for 1 hour with 3.15nA standard deviation of 108.2nA mean in the full-oxygen state and 0.14nA standard deviation of 1.33nA mean in the zero-oxygen state. Also, the fabricated sensor showed a good linearity with a correlation coefficient of 0.997. The LabVIEW-based measurement system composed to voltage supply module, amplifier module, DMM module, and temperature sensing module. In order to measure the cellular respiration level, the measurement program using LabVIEW was made. The ratio of uncoupled cellular oxygen consumption rate per coupled cellular oxygen consumption rate obtained by the fabricated sensors showed 1.96 which is almost the same as the value obtained from a commercial Oxygen-2K.

Enhanced performance of microbolometer using coupled feed horn antenna

In the paper, we improved the performance of the microbolometer using coupled feed horn antenna. The response time of the device was improved by reducing thermal time constant as the area of the absorption layer was reduced. We designed the shape of an absorption layer as circular structure in order to reduce the coupling loss between the antenna and the bolometer. A supporting leg for thermal isolation also has circular structure and its length increased up to 82micrometers , it reduced the thermal conductance to 4.65x 10-8[W/K]. The directivity of the designed antenna has 20.8dB. So the detectivity of the bolometer was improved to 2.37x 10-9 [cm ROOT(Hz)/W] as the noise characteristics of the bolometer was enhanced by coupling feed horn antenna. The fabrication of the bolometer are carried out by a surface micromachining method that uses a polyimide as a sacrificial layer. The absorption layer material of the bolometer is VOx and its TCR value has above 2%/K. The 3-D feed horn antenna structure can be constructed by using a PMER negative photoresist. The antenna and the bolometer can be bonded by Au-Au flip chip bonding method.

Fabrication method of 3D Feed horn shape MEMS antenna array using MRPBI system and application for microbolometer

A 3D Feed horn shape MEMS antenna has some attractive features for array application, which can be used to improve microbolometer performance. Since MEMS technology have been faced many difficulties to fabrication of 3D feed horn shape MEMS antenna array itself. The purpose of this paper is to propose a new fabrication method to realize a 3D feed horn shape MEMS antenna array using a MRPBI(Mirror Reflected Parallel Beam Illuminator) system with an ultra-slow-rotated and inclined x-y-z stage. A high-aspect-ratio 300 micrometers sidewalls had been fabricated using SU-8 negative photo resist. It can be demonstrated to feasibility of realize 3D feed horn shape MEMS antenna array fabrication. In order to study the effect of this novel technique, the 3D feed horn shape MEMS antenna array had been simulated with HFSS(High Frequency Structure Simulator) tools and then compared with traditional 3D theoretical antenna models. As a result, it seems possible to use a 3D feed horn shape MEMS antenna at the tera hertz band to improve microbolometer performance and optical MEMS device fabrication.