Sensors and Actuators B 180 (2013) 35–42 Contents lists available at SciVerse ScienceDirect Sensors and Actuators B: Chemical journa l h o mepage: www.elsevier.com/locate/snb Integration of organic opto-electrowetting and poly(ethylene) glycol diacrylate (PEGDA) microfluidics for droplets manipulation Tung-Ming Yu a,∗ , Shih-Mo Yang a , Chien-Yu Fu c , Ming-Huei Liu d , Long Hsu a , Hwan-You Chang c , Cheng-Hsien Liu b,∗ a Department of Electrophysics, National Chiao-Tung University, No. 1001, University Road, Hsinchu, 300, Taiwan, ROC b Department of Power Mechanical Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC c Institute of molecular medicine, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC d Sinonar Corp., No. 8, Section 1, Prosperity Road, Hsinchu Science Park, Hsinchu, 30078, Taiwan, ROC a r t i c l e i n f o Article history: Received 31 August 2011 Received in revised form 11 December 2011 Accepted 19 December 2011 Available online 26 December 2011 Keywords: Opto-electrowetting (OEW) TiOPc Photo-conductor Electrowetting on dielectric (EWOD) Dielectrophoresis (DEP) Poly(ethylene) glycol diacrylate (PEGDA) a b s t r a c t This paper reports a fabrication technology which integrates organic opto-electrowetting (OEW) with PEGDA-based microfluidics between stacked ITO glass chips for droplets generation and manipulation. Organic OEW can be realized by using titanium oxide phthalocyanine (TiOPc) as a photoconductive layer. Optical images can be projected on an organic OEW area to induce the local virtual electrodes which reduce the surface energy for actuating droplets. Low-molecular-weight (LMW) PEGDA (poly(ethylene) glycol diacrylate) material is used to form stable and biocompatible microchannels between the stacked ITO glass chips by UV photopolymerization process. PEGDA-based microfluidics provides a simpler way to enhance droplets applications in organic OEW. We demonstrate (1) the droplet formation in PEGDA microstructure, (2) the motion of droplet-in-air and droplet-in-oil operated by TiOPc OEW in this platform. This technology requires only spin-coating and UV exposure and is more cost-effective than previous methods. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Droplet-based systems have been mainly studied in the well calibrated droplet formation and the droplet manipulation in microfluidics [1]. Different approaches of droplet forma- tion can produce many kinds of droplets, such as liquid and oil droplets, for material science and biochemical applications. T-junctions and flow-focus microstructures have been compre- hensively designed for droplet formation and fabricated by silicon etching or soft lithography process [2–6]. Electrowetting (EW) and dielectrophoresis (DEP) can provide droplet manipulation on the electrode-patterned substrate for lab-on-a-chip applications. Elec- trowetting technology has accomplished several fluidic functions in handling and actuating droplets, such as droplet transporta- tion, mixing, and separation [7–11]. Electrical control without moving parts has advantages over traditional mechanical con- trol with pumps and valves, which may cause mechanical issues, such as structural failing, clogging, leaking and unwanted mix- ing among different chemical reagents. DEP utilizes the liquid ∗ Corresponding author. Tel.: +886 3 5715131x33706. E-mail addresses: ark.ep96g@g2.nctu.edu.tw (T.-M. Yu), liuch@pme.nthu.edu.tw (C.-H. Liu). electrical properties and non-uniform electrical field distribution to actuate either non-conductive or dielectric droplets [12]. In recent years, the advanced technologies like opto-electrowetting (OEW) and optoelectronic tweezers (OET) have been developed to produce light-induced electrowetting and DEP forces for droplets manipulation [13–19]. Wu’s group firstly demonstrated OEW by integrating amorphous silicon (a-Si) as a photoconductor into electrowetting on dielectrics (EWOD) devices [14]. By projecting optical images to alternate conductivity of the photoconductor layer, virtual electrodes can be formed to induce OEW and may replace the complex physical electrodes required for compli- cated signal control in electrowetting systems. In this study, we focus on integrating droplets formation and OEW with a new and cost-effective fabrication process suitable for biological appli- cations. Two technologies, TiOPc-based OEW and PEGDA-based microfluidic chip, are implemented for this purpose. The TiOPc organic photoconductor provides an alternative for OEW appli- cations because of its many advantages, including non-toxicity, low cost, easy coating process, flexibility, and high photosensitivity [20–23]. In previous microfluidic chips for droplet formation, sili- con etching, photolithography and polydimethylsiloxane (PDMS) molding processes are the common fabrication methods. In the a- Si based optoelectronic tweezers (OET) systems [24–30], the SU-8 microstructure is patterned on the ITO glass and adhered to the 0925-4005/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2011.12.059