Digital Electrophoresis of Charged Droplets

Abstract

A digital microfluidic system based on a direct electric charging and subsequent electrophoretic manipulation of droplets is made by simple fabrication at low cost. Digitally controlled two-dimensional droplet motions are realized by digital polarity control of an array of electrodes. By independent control of droplets and colorimetric detection, the coalescence and mixing of droplets is analyzed quantitatively. The gelation of sodium alginate and the crystallization of calcium carbonate by multiple droplet translations and coalescence and the actuation of glassy carbon beads are demonstrated to show the versatile manipulation capability of the proposed technology. Finally, we discuss the implications and potentials of the present technology.

Contact Charging and Electrphoresis of a Glassy Carbon Microsphere

“…에서 활발히 연구되고 있다 [1][2][3][4][5][6][7][8][9][10][11][12]. 액적 접촉충전 현상 기반의 미세 유체 기술은 개별 액적을 전기를 이용해 다루는 디지털 미세유체 기 술의 한 분야로 [13,14], 채널 내 액적을 다루는 액적 미세유체 (Droplet Microfluidics) [15,16] 기술과는 다르며 기존 미세유체 기술 들의 단점을 극복할 수 있어 새로운 대안 기술로 제시되고 있는 신 기술 이다 [17,18].…”

Next generation digital microfluidic technology: Electrophoresis of charged droplets

“…Modeling of drop/particle motion experiencing the contact charging phenomenon is one of the key subjects in this field [4][5][6]66,[74][75][76][77][78][79][80][81][82]. In microfluidics field, the direct contact charging is used to manipulate droplet [38,[83][84][85][86] or particle motions [20,75] in microchannels in addition to digital microfluidic approaches [6,23,70,77,[87][88][89]. The details of each category will be covered in the following fundamentals and applications section.…”

“…Later, Im et al resolved this issue by decreasing system size and demonstrated various biochemical applications such as hydrogel and crystal formation as shown in Fig. 6 [23]. Because any conducting droplet can be handled by the ECD method as shown in Fig.…”

“…The droplet contact charging phenomenon, referred to as ' electrophoresis of a charged droplet (ECD) [4]' or ' contact charge electrophoresis (CCEP) [20]' , has many advantageous features as a new digital microfluidic technology [4,[21][22][23]. First, ECD is free from surface contamination.…”

Rotary motion of a micro-solid particle under a stationary difference of electric potential

“…3 Numerous studies [3][4][5][6][7][8][9][10][11][12][13] have reported various modes of droplet motion between electrodes using both experimental and numerical methods. A droplet behaves as an electrical charge-carrier between a pair of electrodes in an oil medium as an insulator.…”