Lab-on-a-display: a new microparticle manipulation platform using a liquid crystal display (LCD)

Abstract

This paper reports a new portable microfluidic platform, ''lab-on-a-display,'' that microparticles are manipulated by optoelectronic tweezers (OET) on a liquid crystal display (LCD). The OET has been constructed by assembling a ground layer, a liquid chamber, and a photoconductive layer. Without lens or optical alignments, the LCD image directly forms virtual electrodes on the photoconductive layer for dielectrophoretic manipulation. The lab-on-a-display was first realized by a conventional monochromatic LCD module and a light source brighter than 5,000 lux. It was successfully applied to the programmable manipulation of 45 lm polystyrene beads; more than 100 particles were transported with an optical imagedriven control, following the moving edge of the image at every moment. The effects of bead size and bias voltage on the manipulation speed were also investigated. Due to the portability and compatibility for disposable applications, this new platform has potential for programmable particle manipulation or chip-based bioprocessing including cell separation and bead-based analysis.

Micro and Nano Manipulation and Assembly by Optically Induced Electrokinetics

“…Static light patterns used to trigger the ODEP force can be generated through a photomask [22], a diaphragm [31], or a single focused laser spot [25,32]. Dynamic or programmable manipulation can be achieved by a DMD [18,33,34], a projector [35,36], or a liquid-crystalbased spatial light modulator [37,38]. Additional optical components, including an objective lens, are usually needed to focus light patterns on to the photosensitive layer to obtain a resolution of 1-20 μm [19].…”

Optoelectrofluidic field separation based on light-intensity gradients

“…The photoconductive layer comprises a few different layers; a 180-nm-thick ITO layer, a 50-nm-thick n + doped a-Si:H, a 1-m-thick intrinsic a-Si:H, a 20-nm-thick silicon nitride. 15 A conventional projector ͑VPL-CX5, SONY͒ was used as light source to form virtual electrode patterns. The image illuminated from the projector is collimated and focused by a set of two lenses and 10ϫ objective lens ͑NAϭ0.25͒ onto the photoconductive layer.…”

“…While purely electrical DEP particle manipulation based on CMOS chip, 9 microchannels, 6,7,10 and integrated microsystems 11 have been extensively developed, optoelectronic DEP methods such as optical dielectrophoresis ͑ODEP͒, 12 the image dielectrophoresis, 13 and the optoelectronic tweezers 14 ͑OETs͒ enabled reconfigurable and scalable noninvasive particle manipulation by arbitrarily configurable electrode patterns. The computergenerated virtual electrode patterns, envisioning a laboratory-on-a-display, 15 can provide unlimited user-defined manipulation strategies. Compared with the conventional metal electrodes which usually require numerous miniaturized electrodes or barriers, fabricated by MEMS technology, the optoelectronic technique, which necessitates no fixed electrodes, significantly improves flexibility in controlling bioparticles.…”

Enhanced discrimination of normal oocytes using optically induced pulling-up dielectrophoretic force

“…In the optoelectrofluidic platforms, several mechanisms including optically induced ac electrokinetics [14][15][16][17][18] and electrostatic interactions 19 affect the particle behaviors. Among those mechanisms, the optically induced DEP force was utilized as a driving force for oocyte discrimination in this work.…”

“…The optoelectrofluidic platform utilizes a photoconductive layer on a plate electrode instead of patterned metal electrodes for inducing nonuniform electric field in the medium. [14][15][16] When a dynamic image is projected from a display device including a digital micromirror device 14 and a liquid crystal display 15,16 ͑LCD͒ onto the photoconductive material such as amorphous silicon, the partially illuminated area becomes much more conductive than the other dark area, becoming a virtual electrode to form a nonuniform electric field. Consequently, we can freely manipulate the objects in the medium by several ac electrokinetic mechanisms such as DEP [14][15][16] and ac electro-osmosis.…”