Tung-Ming Yu

Dynamic manipulation and patterning of microparticles and cells by using TiOPc-based optoelectronic dielectrophoresis

We develop light-driven optoelectronic tweezers based on the organic photoconductive material titanium oxide phthalocyanine. These tweezers function based on negative dielectrophoresis (nDEP). The dynamic manipulation of a single microparticle and cell patterning are demonstrated by using this light-driven optoelectronic DEP chip. The adaptive light patterns that drive the optoelectronic DEP onchip are designed by using Flash software to approach appropriate dynamic manipulation. This is also the first reported demonstration, to the best of our knowledge, for successfully patterning such delicate cells from human hepatocellular liver carcinoma cell line HepG2 by using any optoelectronic tweezers.

Light-driven manipulation of picobubbles on a titanium oxide phthalocyanine-based optoelectronic chip

Microbubbles have a variety of applications in science and biological technology. Here, we demonstrate the manipulation of the picoliter gas bubble (picobubble) based on the optoelectronic-mechanism. The organic photoconductive material, titanium oxide phthalocyanine (TiOPc), was developed to make the light-sensitive substrate of this optoelectronic chip. The virtual electrodes are formed by projecting the dynamic light pattern onto TiOPc layer for generating the desired nonuniform electric field. The picobubble suspended in silicone oil can be manipulated with the velocity of 40–50 μm/s. The driving force up to 160 pico-Newtons could be generated for manipulating a gas bubble of 300 picoliters.

Moldless PEGDA-Based Optoelectrofluidic Platform for Microparticle Selection

This paper reports on an optoelectrofluidic platform which consists of the organic photoconductive material, titanium oxide phthalocyanine (TiOPc), and the photocrosslinkable polymer, poly (ethylene glycol) diacrylate (PEGDA). TiOPc simplifies the fabrication process of the optoelectronic chip due to requiring only a single spin-coating step. PEGDA is applied to embed the moldless PEGDA-based microchannel between the top ITO glass and the bottom TiOPc substrate. A real-time control interface via a touch panel screen is utilized to select the target 15 μm polystyrene particles. When the microparticles flow to an illuminating light bar, which is oblique to the microfluidic flow path, the lateral driving force diverts the microparticles. Two light patterns, the switching oblique light bar and the optoelectronic ladder phenomenon, are designed to demonstrate the features. This work integrating the new material design, TiOPc and PEGDA, and the ability of mobile microparticle manipulation demonstrates the potential of optoelectronic approach.

Concentration of Magnetic Beads Utilizing Light-Induced Electro-Osmosis Flow

Magnetic beads are widely utilized for separating biomolecules, DNA and RNA. Traditionally, bulk magnet is utilized for manipulation these particles but when it comes to microscale bulk magnet is not the efficient method. Here, we utilize an organic photoconductive material, TiOPc, to generate light-induced electro-osmosis flow on chip. The fabrication process is convenient to be handled by the researchers and biologists without cleanroom IC fabrication facility. When specifically designed light pattern is projected onto the TiOPc substrate, the conductivity of the organic material layer within the illuminating region increases and the charges are locally assembled on its surface to form a virtual electrode. With an external ac voltage of 5 Vpp at 10 kHz, numerous magnetic beads are attracted from the nonilluminating region toward the center of light-pattern illuminating region. Driven by the moving light image, the grouped magnetic beads can be manipulated and merged in a desired way or direction. The light manipulation process provides a flexible and convenient approach for in vitro control of magnetic beads. We expect that this light-driven technology would display a multifunctional platform for manipulation of microparticles.

Integration of organic opto-electrowetting and poly(ethylene) glycol diacrylate (PEGDA) microfluidics for droplet manipulation

This paper reports a fabrication technology which integrates organic opto-electrowetting (OEW) with PEGDA-based microfluidics between stacked ITO glass chips for droplet 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. Low-molecular-weight (LMW) PEGDA 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 droplet-in-oil applications in organic OEW. This technology requires only spin-coating and photolithography and is more cost-effective than previous methods.

A miniaturized optically-induced fluorescence-activated cell sorter

We integrate the concept of liquid light-driven approach and a cell fluorescent detection system to sort different labeled color HepG2 and 3T3 cells. The optoelectroosmosis flow (OEOF) method would drive the liquid and reverse the flow direction immediately only with light pattern movement. A dielectrophoresis (DEP) force is applied to focal the moving cells as a line. A LabVIEW program would detect the fluorescent cell color and switch the projected light pattern automatically to manipulate the mobile cell real-time. After the OEOF operation, the selected cell is able to push a lateral displacement with 120µm distance against original direction. Based on these four features, this article demonstrates a potential for cells sorting with light driving approaches.

The integration of TiOPc-based optoelectronic tweezers and optoelectrowetting with frequency modulation

This paper reports the platform which combines organic photocoductor-based optoelectrowetting (OEW) and optoelectronic tweezers (OET) by spin-coating titanium oxide phthalocyanine (TiOPc) as a photoconductive layer for realizing the manipulation of microparticles and droplets in a single chip. By producing specific image-induced virtual electrodes and modulating the frequency of the electric field on this device, dielectrophoresis (DEP) and electrowetting (EW) can be selected to become dominant force acting on microparticles and droplets. We demonstrate two kinds of operation modes: (1) In OET mode, micropaticles are concentrated by using strip-shaped optical images and the applied voltage in the high frequency range. (2) In OEW mode, droplets are actuated by employing square-shaped optical images and the applied voltage in the low frequency range.

Organic Optoelectronic Platform for Droplets Actuation and Cells Manipulation

This paper reports the organic optoelectronic platform which integrates optoelectrowetting (OEW) and optoelectronic tweezers (OET) by spin-coating titanium oxide phthalocyanine (TiOPc) as a photoconductive layer for realizing the manipulation of cells and the actuation of droplets in a single chip.

Optical-driven vortex as a microparticle concentator

The light-driven optoelectronic vortex concept is firstly reported in this article. Utilizing illuminating light image to manipulate the liquid flow direction without any mechanic components is the feature of this design, named as optoelectroosmosis flow (OEOF). With the simple spin-coating process to form a thin organic photoconductive material, TiOPc, on the designed ITO pattern, the projected light pattern is able to generate dynamic virtual electrode on the substrate surface. Besides, the non-uniform electric field distribution would drive the ions moving with slip velocity. Furthermore, two light driven flows with different directions are able to form a clockwise or counter clockwise for microparticles concentration from non-illuminating toward illuminating region. This convenient approach of light-driven flow and microparticle concentration without any mechanical component enlarge the scope of liquid manipulation field.

Organic photoconductive dielectrophoresis by using titanium oxide phthalocyanine for micro-particles manupulation

This paper reports our updating development for the organic photoconductive dielectrophoresis (OPDEP) by using titanium oxide phthalocyanine (TiOPc) material for the manipulation of micro-objects. The advantages of organic photoconductive material include non-toxicity, low cost, easy coating fabrication, flexibility, panchromaticity and high photosensitivity [1]. TiOPc has the high photoconductivity and the optical absorptions in the near infrared region (550 – 850 nm) to be a candidate of the light-sensitive charge generation layer. OPDEP chip is easily mass-produced by using a spin-coating process. Here, we demonstrate two kinds of the manipulations of micro-particles on our OPDEP chip. Firstly, the trapping and movement of single micro-particle is achieved by the ring shaped virtual electrode. Secondly, the steel rim shaped virtual electrode is designed to rotate micro-particles and characterize the OPDEP induced force.