Malaysian Journal of Analytical Sciences Vol 23 No 2 (2019): 362 - 375

DOI: 10.17576/mjas-2019-2302-20

 

 

 

Nd:YAG LASER FABRICATION OF SILICON ELECTRODE PLATES FOR A COMBINED-MODE MICRO DIRECT METHANOL FUEL CELL

 

(Fabrikasi Plat Elektrod Silikon dengan Laser Nd:YAG untuk Sel Bahan Api Metanol Langsung Mikro Bermod Gabungan)

 

Umi Azmah Hasran¹*, Siti Kartom Kamarudin^1,3, Burhanuddin Yeop Majlis², Wan Ramli Wan Daud³, Abdul Amir Hassan Kadhum³, Gandi Sugandi⁴

 

¹Fuel Cell Institute

²Institute of Microengineering and Nanoelectronics

³Department of Chemical and Process Engineering

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

⁴Research Center for Electronics and Telecommunication

Lembaga Ilmu Pengetahuan Indonesia, Bandung, Indonesia

 

*Corresponding author:  umi.h@ukm.edu.my

 

 

Received: 13 April 2017; Accepted: 17 April 2018

 

 

Abstract

A silicon wafer was microfabricated to produce a new combined-mode flow field for the purpose of distributing methanol fuel throughout the anode side of a micro direct methanol fuel cell (DMFC). Active mode of operation, which generally produces more power, is more suited to higher power requirements compared with the passive mode. Different power outputs using different modes may be required during cell operation by devices that can potentially use the micro DMFC. The new flow field design in the electrode structure of the micro DMFC must manage the methanol fuel transport in either active or passive mode. The flow field area was designed to obtain 50% of the 1 cm² active reaction area of the membrane electrode assembly. The proposed design was simulated using COMSOL multi-physics software and microfabricated by incorporating two flow field designs on the anode plate, namely, the grid flow field for the active mode and the porous flow field for the passive mode. The silicon wafer used to produce the electrode plate was a <100> p-type single-sided polished substrate and the MEMS-based microfabrication process to form the required electrode structures was dry etching with laser ablation. The current collector layers used were titanium/copper with a thickness of 1.1 μm and gold with a thickness of 0.18 µm. The completed single-cell micro DMFC obtained a maximum performance of 1.86 mW/cm² at a voltage of 138.7 mV.

 

Keywords:  anode flow field, MEMS technology, active mode, passive mode, dry etching technique

 

Abstrak

Wafer silikon telah dimikrofabrikasi untuk menghasilkan medan aliran baru berbentuk mod gabungan bagi pengedaran bahan api metanol ke seluruh bahagian anod di dalam DMFC mikro. Mod operasi aktif, yang umumnya menghasilkan lebih banyak kuasa, adalah lebih sesuai dengan keperluan kuasa yang lebih tinggi berbanding mod operasi pasif. Output kuasa yang berbeza menggunakan mod yang berbeza dijangka diperlukan semasa operasi sel oleh peranti yang berpotensi menggunakan DMFC mikro. Reka bentuk medan aliran baru dalam struktur elektro DMFC mikro ini mesti menguruskan pengangkutan bahan api metanol sama ada dalam mod aktif atau pasif semasa operasi. Kawasan medan aliran direka untuk mendapatkan ~ 50% daripada kawasan reaksi aktif 1 cm² himpunan elektrod membran. Reka bentuk baru ini disimulasikan menggunakan perisian multifizik COMSOL dan dimikrofabrikasi dengan menggabungkan dua reka bentuk medan aliran pada sekeping plat anod, iaitu medan aliran grid untuk mod aktif dan medan aliran poros untuk mod pasif. Wafer silikon yang digunakan untuk menghasilkan plat elektrod adalah substrat <100> tergilap sebelah jenis-p dan proses mikrofabrikasi yang berasaskan MEMS untuk membentuk struktur elektrod yang diperlukan adalah punaran kering dengan ablasi laser. Lapisan pengumpul arus adalah titanium/tembaga dengan ketebalan 1.1 μm dan emas dengan ketebalan 0.18 μm. Sel tunggal DMFC mikro yang telah disiapkan dapat memberikan prestasi maksimum 1.86 mW/cm² pada voltan 138.7 mV.

 

Kata kunci:  medan aliran anod, teknologi MEMS, mod aktif, mod pasif, proses punaran kering

 

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