Journal of Power Sources 193 (2009) 150–154 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Short communication Fabrication of flexible micro-sensors and flow field of stainless steel-based micro-reformer by micro-electro-mechanical-systems process Chi-Yuan Lee a,∗ , Shuo-Jen Lee a , Chia-Chieh Shen a , Wei-Mon Yan b , Fang-Bor Weng a , Guo-Bin Jung a , Chien-Heng Lin a a Department of Mechanical Engineering, Yuan Ze Fuel Cell Center, Yuan Ze University, 135 Yuan-Tung Road, Chungli, 320 Taoyuan, Taiwan, ROC b Department of Mechatronic Engineering, Huafan University, Taipei, Taiwan, ROC article info Article history: Received 9 October 2008 Received in revised form 12 February 2009 Accepted 16 February 2009 Available online 5 March 2009 Keywords: MEMS Flexible micro-sensors Micro-reformer abstract Recent advances in micro-fuel cells have increased the demand for hydrogen. Therefore, a micro-reformer must be developed. Numerous portable electric devices are extremely small and reformers must therefore be shrunk and combined with micro-fuel cells. The mass production of micro-reformers raises various problems that are yet to be solved, such as the measurement of their internal temperature and flow rate. Such issues influence the efficiency of the micro-reformers. To our knowledge, no investigation has yet properly elucidated the internal operation of micro-reformers. Accordingly, in this work, a flexible micro- temperature sensor, a micro-heater, a micro-flow sensor and the flow field of a stainless steel-based micro-reformer were fabricated by micro-electro-mechanical-systems (MEMS) fabrication technique. The fabrication technique has the advantages of (1) small size, (2) flexible but precise measurement positions, and (3) mass production process. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Stainless steel has recently been used as a substrate in var- ious fabrication processes for the following reasons. It is easily mass-produced and is inexpensive; it is processed and packaged more easily than a silicon substrate, and it effectively prevents gas leakage. Although stainless steel does not have a better corrosion resistance than silicon or noble metal, it is preferred as a substrate over other metals because of its cost and ease of fabrication. The reaction between hydrocarbon and water is endothermic, and so the reactant must be heated to induce the reaction. The reaction generates more hydrogen as the temperature is increased. Park designed a steam reformer that exploits external heat [1,2]. This reformer, which is operated at a temperature of 260 ◦ C, has an S/C ratio of 1.1 and a hydrogen production rate of 0.498moleh -1 ; it can supply a 15W fuel cell. Another steam reformer consists of four parts—a fuel evaporation chamber, a heat exchange chamber, a catalyst burning chamber and a steam reforming chamber. The cat- alyst burning chamber supplies heat to enable the steam reforming chamber to maintain the heat required for reforming. When it is operated at temperatures of 230–260 ◦ C with an S/C ratio of 1.1, its methyl conversion rate is close to 99%, and its hydrogen production ∗ Corresponding author. Tel.: +886 3 4638800x2478; fax: +886 3 4558013. E-mail addresses: cylee@saturn.yzu.edu.tw, leecyu@mems.iam.ntu.edu.tw (C.-Y. Lee). rate is 0.88 mole h -1 ; therefore, it can supply a 59 W fuel cell. Since platinum is required, the production cost is high. In 2000, Yang [3] utilized bulk-micro-machining to produce micro-channels, and used a platinum thin-film sensor on the micro- channels to measure the distribution of temperature in the channel. In 2006, Kim and Kwon [4] developed a system that comprised a methanol–steam reformer, a catalytic combustor, a preferential oxidation (PROX) reactor, and a polymer electrolyte membrane fuel cell (PEMFC). A methanol reformer is crucial supplying hydro- gen, and it integrates a pre-heater, vaporizing/reforming channels and a catalytic combustor. All components were fabricated using micro-electro-mechanical-systems (MEMS) fabrication technolo- gies combined with catalyst loading processes. In 2005, Bruschi et al. [5] utilized micro-temperature sen- sors and micro-heaters on a stainless steel substrate, integrating them with micro-channels and circuit systems. The temperatures upstream and downstream of the channels were measured under various gas flow rates. The results established that when the gas flow rate inside the micro-channels was less than 200 sccm, it was positively correlated with the output voltage of the system. Scholer et al. [6] employed MEMS to fabricate a micro-platinum flow sensor on glass, and utilized Computational Fluid Dynamics Research Corporation (CFDRC) software to compare and contrast the simulation results with the experimental measurements of flow. In 2007, Terao et al. [7] applied MEMS to fabricate a micro-flow sensor on a reformer. He utilized water flow to find the measure- 0378-7753/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2009.02.065