A Novel Micro Dispensing Chip for Microarray Fabrication

The paper proposes a novel design concept and fabrication method of micro dispensing chip. The filling process is performed by capillary force without extra energy, greatly reducing the complexity of design and operation. The annular interspaces around the nozzles in the chip can help the droplet formation on the hydrophilic surfaces, and the step conjunction between the channel and the reservoir can reduce the fluid refluence to the inlet. The fabrication of the silicon chip with 25 reservoirs has been successfully completed by deep reactive ion etching (DRIE). Polydimethyl silocane (PDMS) membrane can tightly bond the silicon surface to form a sealed channel in the vacuum environment at 150degC in 3 hrs. By applying 10 kPa pressure with the duration of 1000 mus, the chip could simultaneously produce 5 times 5 array on the glass within the area of 3.4mm times 3.4mm. The coefficient of variation (CV) for intensities within 25 individual fluid spots can reach 4.1% and the CV for diameters is as low as 3.8%. The results from both computational fluid dynamics (CFD) simulations and dispensing experiments demonstrated that the fabricated silicon chip can produce uniform microarrays with high stability and good reproducibility in a short time