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.
    Microfluidics and Nanofluidics 07/2012; 13(1):1-9. DOI:10.1007/s10404-012-0935-5 · 2.53 Impact Factor
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    • "Later development introduces new phototransistor consisting of single-crystalline bipolar junction transistors with high photoconductivity in place of amorphous silicon, which allows the OET devices operate in integrated cell culture environments. As a paradigm, efficient cell trapping of live HeLa and Jurkat cells has been realized in standard cell culture media (e.g., phosphate buffered saline and Dulbecco’s modified eagle’s medium).67 In a similar route, a group in KAIST has turned a regular liquid crystal display (LCD) into the OET configuration. "
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    ABSTRACT: This review is motivated by the growing demand for low-cost, easy-to-use, compact-size yet powerful micro-nanofabrication technology to address emerging challenges of fundamental biology and translational medicine in regular laboratory settings. Recent advancements in the field benefit considerably from rapidly expanding material selections, ranging from inorganics to organics and from nanoparticles to self-assembled molecules. Meanwhile a great number of novel methodologies, employing off-the-shelf consumer electronics, intriguing interfacial phenomena, bottom-up self-assembly principles, etc., have been implemented to transit micro-nanofabrication from a cleanroom environment to a desktop setup. Furthermore, the latest application of micro-nanofabrication to emerging biomedical research will be presented in detail, which includes point-of-care diagnostics, on-chip cell culture as well as bio-manipulation. While significant progresses have been made in the rapidly growing field, both apparent and unrevealed roadblocks will need to be addressed in the future. We conclude this review by offering our perspectives on the current technical challenges and future research opportunities.
    Annals of Biomedical Engineering 02/2011; 39(2):600-20. DOI:10.1007/s10439-010-0218-9 · 3.23 Impact Factor
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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.
    Advances in OptoElectronics 01/2011; 2011(1687-563X). DOI:10.1155/2011/482483
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