Integration of the micro thermal sensor and porous silicon as the gas diffusion layer for micro fuel cell

Abstract

This work employs porous silicon as a gas diffusion layer (GDL) in a micro proton exchange membrane fuel cell (muPEMFC) and a micro direct methanol fuel cell (muDMFC). Pt catalyst is deposited on the surface of, and inside, the porous silicon to improve its conductivity. Porous silicon with Pt catalyst replaces traditional GDL, and the Pt metal that remains on the rib is used to form a micro thermal sensor in a single lithographic process. The GDL was replaced by porous silicon and used in a muPEMFC and muDMFC. Wet etching is applied to a 500 mum-thick layer of silicon to yield fuel channels with a depth of 450 mum and a width of 200 mum. The pores in the fabricated structure had a diameter of 10 mum; the thickness of the structure was 50 mum. Therefore, the GDLs of the fuel cell were fabricated using macro-porous silicon technology. Porous silicon was fabricated by photoelectrochemical porous silicon etching. The top-side of the fuel channel was exposed to light from a halogen lamp. The porous structure was fabricated at the bottom of the fuel channel and patterned by anodization; and the micro thermal sensors were integrated on the rib. The experimental results demonstrated that the maximums power density of muDMFC and muPEMFC were 1.784 mW/cm2 and 9.37 mW/cm2. 30SCCM and 2 M methanol were used with 10 mum holes, various humidities and heating temperatures.