Microfluidic study of the liquid transfer properties of reservoir pins for use in microarraying

摘要

The technique of microarraying involves laying down genetic elements onto a solid substrate for DNA analysis on a massively parallel scale. A pin-based robotic platform for bioMEMS in used to prepare microarrays by transferring liquid samples from microtire plates to array patterns on the surfaces of coated glass slides. The liquid dries to form spots diameter <200 μm. This paper presents the design and performance of reservoir pins with particular emphasis on microfluidics and the influence of pin geometry and surface topology. In the newly developed manufacturing process a pin is produced by (a) wet etching of tungsten wire, followed by (b) micromachining with a focused laser to produce a capillary channel structure and a microreservoir. The pin has a flat end 100 μm in diameter from which a 600 μm long capillary channel, 15 μm wide leads up the pin to a reservoir. The pin capacity is 50 nanolitres of fluid containing DNA, and at least 50 spots can be printed before replenishing the reservoir. A typical robot holds 16 - 48 pins. Scanning electron micrographs of the metal surface show roughness on the scale of 5 μm. However, the pins give consistent and reproducible spotting performance. In this paper comparisons will be made between the real life performance of the pins on the robotic platform with observations and measurements make using a video microscope system, and an assessment of the prospects for bioMEMS and further miniaturization of this technology.