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

Abstract

We present a method to discriminate normal oocytes in an optoelectrofluidic platform based on the optically induced positive dielectrophoresis ͑DEP͒ for in vitro fertilization. By combining the gravity with a pulling-up DEP force that is induced by dynamic image projected from a liquid crystal display, the discrimination performance could be enhanced due to the reduction in friction force acting on the oocytes that are relatively large and heavy cells being affected by the gravity field. The voltage condition of 10 V bias at 1 MHz was applied for moving normal oocytes. The increased difference of moving velocity between normal and starved abnormal oocytes allows us to discriminate the normal ones spontaneously under the moving image pattern. This approach can be useful to develop an automatic and interactive selection tool of fertilizable oocytes.

dc electrokinetic transport of cylindrical cells in straight microchannels

“…This kind of electrokinetic phenomenon has been widely used to manipulate spherical particles in microfluidics such as particle trapping, [31][32][33][34][35] separation, 16,[35][36][37][38][39][40][41] focusing, 14,18,35 and cell discrimination. 42,43 Previous numerical and experimental studies demonstrate that the DEP effect should be taken into account to study the electrokinetic transport of spherical particles where nonuniform electric fields are present. 11,15 Recently, a DEP-induced alignment phenomenon of nanowires and carbon nanotubes [44][45][46][47][48][49] to external electric fields was experimentally observed, indicating a significant DEP effect on the motion of cylindrical particles subjected to external electric fields.…”

Simultaneous separation and concentration of micro- and nano-particles by optically induced electrokinetics

“…It has the ability to dynamically create real-time, reconfigurable, 'virtual' electrodes and the generated DEP force can span a large working area on the chip, as well as using ∼100,000 times less optical power than laser-based optical tweezers. The OET chip has been employed to enable massively parallel manipulation of micro-/nano-entities using virtual electrodes that are optically projected from a personal computer-based system with any desired geometric pattern, such as for the manipulation and separation of cells [17], inducing self-rotation of Melan-a cells [18], separation of nanowires [19], dynamic patterning of gold nanoparticles [20], fabrication of micrometer-and nanometer-scale polymer structures [21], and separation of polystyrene beads by a negative DEP force [22]. Considering that all of the optically induced electrokinetics (OEK) forces, such as optically induced DEP, AC electroosmosis (ACEO), and electrothermal (ET) flows, will simultaneously exist in the experimental process (e.g., see [23][24][25]), we herein define an OET chip with the more general term of an "OEK chip" in this paper.…”

Exploitation of physical and chemical constraints for three-dimensional microtissue construction in microfluidics

“…Chiou et al 60 proposed an optically induced DEP method where the gradient of the electric field is generated using an optical image on a photodiode surface. An optoelectrofluidic platform for differentiation of normal oocytes using a pDEP force that is induced by a dynamic image projected from a liquid crystal display was proposed by Hwang et al 61 Another method used the spatial or temporal conductivity gradient for generating gradients of an electric field and hence dielectrophoretic force. 62,63 A classical or conventional method to generate gradients of the electric field is using a nonuniform shape of the electrodes.…”