PHOTOTRANSISTOR BASED OPTOELECTRONIC TWEEZERS FOR CELLMANIPULATION IN HIGHLY CONDUCTIVE SOLUTION

1. Transducer & Eurosensors 07 PHOTOTRANSISTOR BASED OPTOELECTRONIC TWEEZERS FOR CELLMANIPULATION IN HIGHLY CONDUCTIVE SOLUTION H. Y. Hsu, A. T. Ohta, P. Y. Chiou, A. Jamshidi, andM. C.Wu Berkeley Sensor and Actuator Center and Dept. of Elec. Engineering and Computer Sciences Berkeley, California, USA Reporter：Tzu-Yu Chao

2. Outline Introduction Principle Fabrication Method Result Conclusion

3. Introduction Cell manipulation technique Electrode-based dielectrophoresis (DEP) high throughput lack the flexibility of optical control Optic Tweezers high resolution and flexibility limited manipulation area Optoelectronic tweezers (OET) utilized optically-induced dielectrophresis flexibility of optical control increase parallel manipulation capability REF: Strategies for dielectrophoretic separation in laboratory-on-a-chip systems University of Surrey, Guildford, United Kingdom REF: Observation of a single-beam gradient force optical trap for dielectric particles A. Ashkin et. al. , Holmdel, New Jersey 07733 REF: Massively parallel manipulation of single cells and microparticles using optical images Pei Yu Chiou, et. al. University of California at Berkeley, USA. Nature Letter

4. Principle Light Side Zph < Zliquid Vph < Vliquid Dark Side Zph > Zliquid Vph > Vliquid OET Use amorphous silicon as photoconductor =>need use low conductivity medium material =>reduce cell viability

5. Phototransistor Model Collector Light Emitter Base One pixel area 10μm x 10μm Phototransistor-based OET Use highly-conductive buffer as cell medium => Medium Ref: http://www.itee.uq.edu.au/~emami/metr2800/

6. Photoconductor (Amorphous Silicon) Required light intensity > 50W/cm2 Phototransistor Required light intensity < 0.3W/cm2

7. Fabrication 2μm-wide trenches

8. Method Light source: 658nm Diode Laser Applying a sinusoidal AC source with frequency of 9MHz Manipulation object: Hela cell (cancer cell) Jurkat cell (T cell) Solution: Phosphate-buffered saline (PBS) Dulbecco’s modified eagle medium (DMEM) both solutions have the same conductivity 1.5 S/m

9. Result Light pattern area: 250 μm x 50 μm

10. Conclusion 1.Developed for operations in highly-conductive solution 2.Required a much lower optical intensity for operation Reference [1] A. Ashkin, J. M. Dziedzic, J. E. Bjorkholm, and S. Chu, "Observation Of A Single-Beam Gradient Force Optical Trap For Dielectric Particles," Optics Letters, vol. 11, pp. 288-290, 1986. [2] M. P. Hughes, "Strategies for dielectrophoretic separation in laboratory-on-a-chip systems," Electrophoresis, vol. 23, pp. 2569-2582, 2002. [3] P. Y. Chiou, A. T. Ohta, and M. C. Wu, "Massively parallel manipulation of single cells and microparticles using optical images," Nature, vol. 436, pp. 370-372, 2005. [4] A. T. Ohta, C. Pei-Yu, A. Jamshidi, H. Hsan-Yin, M. C. Wu, H. L. Phan, S. W. Sherwood, J. M. Yang, and A. N. K. Lau, "Spatial cell discrimination using optoelectronic tweezers,“ presented at 2006 Digest of the LEOS Summer Topical Meetings (IEEE Cat. No. 06TH8863C). IEEE. 2006, pp. 23-4. Piscataway, NJ, USA.