Shuo-Jen Lee

Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10−3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C.

Fabrication of micro temperature sensor and heater in a stainless steel-based micro reformer

Among those problems regarding use of micro reformers that have not yet been solved include reducing their size, decreasing the amount of CO and combining the fuel cell, among others. Therefore, in this work, a micro temperature sensor and a heater are combined inside a stainless steel-based micro reformer to measure the temperature, to improve performance and minimize the concentration of CO. Micro-electro-mechanical-systems (MEMS) of the micro channel type are fabricated on a stainless steel substrate to enhance the methanol conversion ratio. A micro temperature sensor and a heater are placed separately inside a micro reformer. The main advantages of micro temperature sensors are their higher accuracy and sensitivity than those of a traditional thermocouple. Micro temperature sensors and heaters have not been applied in micro reformers and commercial products. Hence, this investigation proposes a novel approach for integrating a micro temperature sensor and a heater in a stainless steel-based micro reformer, to minimize size and optimize performance.

Novel Method for In Situ Monitoring of Thickness of Quartz during Wet Etching

In this work, we present a novel method based on a plate wave sensor for the in situ monitoring of the thickness of quartz membranes during wet etching. Similarly to oscillators and resonators, some acoustic devices require the thickness of quartz membranes to be determined precisely. Precise control of the thickness of quartz membranes during wet etching is important, because the thickness strongly influences post processing and frequency control. Furthermore, the proposed plate wave sensor, allows the thickness of quartz membranes from a few µm to hundreds of µm to be monitored in situ, which depends on the periodicity of an interdigital transducer (IDT). In summary, the proposed method for measuring the thickness of quartz membranes in real time has a high accuracy, is simple to set up and can be mass-produced. Also described herein are the principles of the method used, the detailed process flow, the measurement set up and the simulation and experimental results. The theoretical and measured values differ by an error of less than 1 µm, implying a close correspondence.