Fabrication and measurement system for microarray using Digital Micromirror Device

摘要

We developed a new system that fabricates and measures a microarray using Digital Micromirror Device (DMD). This system can totally automate a microarray process from well fabrication until fluorescence measurement. The microarray was fabricated by maskless photolithography of negative tone photoresist SU-8 exposed by a near ultraviolet ray pattern of the DMD. This method is able to fabricate up to 10,000 wells in one inch square area on a glass plate. Fluorescence of the microarray was sequentially measured by excitation of indivitual well using a blue ray dot of the DMD. Detection of the fluorecent intensity was performed by a photomultiplier tube (PMT). In order to evaluate the mesurement method, we constructed two optical systems. One is a simple transmission type of straight optical axis with a filter pair. The other is a separation type to reflect an excitation ray in 90 deg with a dichroic mirror. For the system evaluation, we mesured a microarray of 25 wells on one inch square (volume is ca. 1μL/well) that were filled up with Lucifer Yellow (a fluorescent material, Ex:428 nm, Em:536 nm) aqueous solution of various concentrations. As a result, the separation type system is able to measure 0.01 mg/mL on signal to noise ratio of 7.51. And lower detection limit of the fluorescent density was 11 times for the transmission type.