FIGURE 1. Device structure used in optoelectronic tweezers.
From the following article:
Massively parallel manipulation of single cells and microparticles using optical images
Pei Yu Chiou, Aaron T. Ohta and Ming C. Wu
Nature 436, 370-372 (21 July 2005)
doi: 10.1038/nature03831
Liquid that contains microscopic particles is sandwiched between the top indium tin oxide (ITO) glass and the bottom photosensitive surface consisting of ITO-coated glass topped with multiple featureless layers: 50 nm of heavily doped hydrogenated amorphous silicon (a-Si:H), 1 µm of undoped a-Si:H, and 20 nm of silicon nitride. The top and bottom surfaces are biased with an a.c. electric signal. The illumination source is an light-emitting diode operating at a wavelength of 625 nm (Lumileds, Luxeon Star/O). The optical images shown on the digital micromirror display (DMD) are focused onto the photosensitive surface and create the non-uniform electric field for DEP manipulation.
