A DNA biochip for on-the-spot multiplexed pathogen identification

Yeung, Siu-Wai; Lee, Thomas Ming-Hung; Cai, Hong; Hsing, I-Ming

The silicon chip (thickness of 400 mm) had two fluid injection holes (top side, diameter of 500 mm, depth of 100 mm) and a chamber (bottom side, length and width of 5 mm, depth of 325 mm) etched by the inductively coupled plasma/deep reactive ion etching (ICP/DRIE) process, see Figure 1A (left panels). Thin-film platinum (100 nm) was patterned on top of the silicon substrate as heater and temperature sensors ( Figure 1A , upper left). The glass chip had platinum pseudoreference and counter electrodes (thickness of 100 nm) as well as four working electrodes made of indium tin oxide (ITO) (thickness of 100 nm), see right panel of Figure 1A . Ultra-violet curing optical cement (Type UV-69, Summers Optical, Hatfield, PA, USA) was used to bond the silicon and glass chips, the curing procedure was in accordance with the manufacturer's instruction. Pipet tips were glued to the fluid injection holes with epoxy ( Figure 1B ).