Optical Addressing of Polymer Beads for Chip-Based Systems

Conventional methods that emerged from microelectronics are now used for fabrication of labon-a-chip devices for applications in chemical and biological studies. Sample localization and arraying within these devices are desired for high throughput screening applications. We developed a novel optical addressing scheme in an electrochemical system to localize polymer beads (0.8-10 μm in diameter) on various semiconductor substrates with a nonlithographic pattern transfer concept. Optical microbeam that is directed on the substrate creates an active local electrode area with a certain charge that is defined by the solid-liquid interface characteristics. This localized charge attracts the oppositely charged objects within electrolyte solution, which helps to form desired object pattern. By using a multibeam system or illumination through a mask a relatively large object arrays can be formed for high throughput chemical or biological applications.