Phototransistor-based optoelectronic tweezers for dynamic cell manipulation in cell culture media

University of California-Berkeley, Berkeley Sensor and Actuator Center, Department of Electrical Engineering and Computer science, 476 Cory Hall, Berkeley, CA 94720, USA.
Lab on a Chip (Impact Factor: 6.12). 01/2010; 10(2):165-72. DOI: 10.1039/b906593h
Source: PubMed


Optoelectronic tweezers (OET), based on light-induced dielectrophoresis, has been shown as a versatile tool for parallel manipulation of micro-particles and cells (P. Y. Chiou, A. T. Ohta and M. C. Wu, Nature, 2005, 436, 370-372). However, the conventional OET device cannot operate in cell culture media or other high-conductivity physiological buffers due to the limited photoconductivity of amorphous silicon. In this paper, we report a new phototransistor-based OET (Ph-OET). Consisting of single-crystalline bipolar junction transistors, the Ph-OET has more than 500x higher photoconductivity than amorphous silicon. Efficient cell trapping of live HeLa and Jurkat cells in Phosphate Buffered Saline (PBS) and Dulbecco's Modified Eagle's Medium (DMEM) has been demonstrated using a digital light projector, with a cell transport speed of 33 microm/sec, indicating a force of 14.5 pN. Optical concentration of cells and real-time control of individually addressable cell arrays have also been realized. Precise control of separation between two cells has also been demonstrated. We envision a new platform for single cell studies using Ph-OET.

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    • "The COPS configuration has wide applications in microfluidic platforms such as cell handling, particle ligand change, etc., as well as particle separation (Hsu et al. 2010; Hakem et al. 2010; Maruyama et al. 2011). The particle behavior during COPS was theoretically estimated and experimentally evaluated in terms of two factors: size and refractive index of the particle (Helmbrecht et al. 2007; Kim et al. 2006, 2008b). "
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    ABSTRACT: This paper describes the optical and hydrodynamic characteristics of particle motion in a cross-type optical particle separator. The retention distance modulated by the optical force on a particle was measured in three dimensions for various vertical and horizontal positions via μ-defocusing digital particle image velocimetry. The experimental data showed that the actual retention distance was smaller than the predicted retention distance under the assumption that the approaching velocity was constant through the cross-section of a microfluidic channel. The retention distance was shown to increase as the injection position of the particle shifted toward the channel side wall at a given vertical position due to a higher residence time within the region of influence of the laser beam. In contrast, the retention distance decreased as the injection position shifted toward the channel top/bottom walls at a given horizontal position. A theoretical modeling study was conducted to support and interpret the experimental measurements. The resolution of the particle separation procedure, which did not require adjusting the flow rate, laser power, or working fluid properties, was studied.
    Full-text · Article · Jul 2012 · Microfluidics and Nanofluidics
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    • "For the direct analysis of salty solutions such as blood plasma, therefore, an optoelectrofluidic device with much higher photoconductivity is necessary. However, the devices developed to date such as a phototransistorbased OET device [79] are so complicated and require high costs and long time for the fabrication. Therefore, more research for developing the optoelectrofluidic devices which can be operated even under physiological conditions should be promoted. "
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    ABSTRACT: This paper presents optoelectrofluidic technologies for manipulation of nanoparticles and biomolecules. Optoelectrofluidics provides an elegant scheme for the programmable manipulation of particles or fluids in microenvironments based on optically induced electrokinetics. Recent progress on the optoelectrofluidic manipulation of nanoobjects, which include nanospheres, nanowires, nanotubes, and biomolecules, is introduced. Some potential applications of the optoelectrofluidic nanoparticle manipulation, such as nanoparticles separation, nanostructures manufacturing, molecular physics, and clinical diagnostics, and their future directions are also discussed.
    Full-text · Article · Nov 2011 · Advances in OptoElectronics
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    • "Recent development of OET technologies also broadened the type of media in which OET can operate. Phototransistor OET enabled OET to function in regular physiological buffers with high electrical conductivity (1.5 S/m) [11]. Floating electrode OET enabled the manipulation of aqueous droplets in electrically insulating media such as oils and air [12] [13]. "
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    ABSTRACT: We report on two types of electrodes that enable the integration of optoelectronic tweezers (OETs) with multilayer poly(dimethylsilane)- (PDMS-) based microfluidic devices. Both types of electrodes, Au-mesh and single-walled carbon nanotube- (SWNT-) embedded PDMS thin film, are optically transparent, electrically conductive, and can be mechanically deformed and provide interfaces to form strong covalent bonding between an OET device and PDMS through standard oxygen plasma treatment. Au-mesh electrodes provide high electrical conductivity and high transparency but are lack of flexibility and allow only small deformation. On the other hand, SWNT-embedded PDMS thin film electrodes provide not only electrical conductivity but also optical transparency and can undergo large mechanical deformation repeatedly without failure. This enables, for the first time, microfluidic integrated OET with on-chip valve and pump functions, which is a critical step for OET-based platforms to conduct more complex and multistep biological and biochemical analyses.
    Full-text · Article · Oct 2011 · Advances in OptoElectronics
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