Research
Microrobots
This project involves the manipulation and the assembly of micro-objects using optically controlled microrobots. Light patterns are used to control the movement of the microrobots. Objectives include the micro-assembly of objects, including live cells, and the parallel, independent control of multiple microrobots in one system.
Videos of the microrobots in action:
For more information, see:
- W. Hu, K. S. Ishii, Q. Fan, and A. T. Ohta, “Hydrogel
microrobots actuated by optically generated vapour bubbles, Lab on a
Chip, vol. 12, no. 19, pp. 3821-3826, 2012.
- K. S. Ishii, W. Hu, and A. T. Ohta, “Cooperative micromanipulation using optically controlled bubble microrobots,” Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pp. 3443-3448, May 2012.
- W. Hu, K. S. Ishii, and A. T. Ohta, “Micro-assembly using optically controlled bubble microrobots in saline solution,” Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pp. 733-738, May 2012.
- W. Hu, K. S. Ishii, and A. T. Ohta, "Micro-assembly using optically controlled bubble microrobots," Applied Physics Letters, vol. 99, p. 094103, 2011.
Cell culturing devices
The cell culturing device project involves the trapping of cells in hydrogel scaffold in order to promote the cultivation of cells in 3D. Advances in cell culturing technology could lead to improved drug and therapy development, along with alternative ways to test live subjects. The project will also give a further insight into cell behavior, which could lead to the cure of various diseases.For more information, see:
- K. S. Ishii, W. Hu, S. A. Namekar, and A. T. Ohta, “An optically
controlled 3D cell culturing system,” Advances
in OptoElectronics, vol. 2011, Article ID 253989, 8 pages, 2011.
doi:10.1155/2011/253989
Optoelectronic tweezers
We are exploring the use of optoelectronic tweezers for live / dead cell sorting for in vitro fertilization. A treatment available to men with sperm of limited mobility or viability is intracytoplasmic sperm injection (ICSI), where fertilization is achieved by injecting a single sperm directly into the oocyte (egg). Thus, the quality of the individual sperm that is selected is of paramount importance, and the challenge is how to distinguish viable from non-viable sperm. Current sperm viability assays are limited by subjectivity, sensitivity, and potential toxicity. Optoelectronic tweezers can non-invasively distinguish between live and dead cells and provide a means of sorting them. We have demonstrated the separation of live and dead sperm even in the absence of motility, as viable non-motile sperm are attracted to OET-induced electric fields, while non-viable sperm are repelled by the same electric fields. Thus, OET sorting is a potential method by which to identify viable non-motile sperm for assisted reproductive technologies.
For more information, see:
- A. T. Ohta et al., “Motile and non-motile sperm diagnostic manipulation using optoelectronic tweezers,” Lab on a Chip, vol. 10, pp. 3213-3217, 2010.
- A. T. Ohta et al., “Optically-controlled cell discrimination and trapping using optoelectronic tweezers,” IEEE Journal of Selected Topics in Quantum Electronics, vol. 13, pp. 235-243, 2007.
- 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.
Tunable RF circuits & devices
This project uses microfluidic tools and techniques to create tunable radio-frequency (RF) circuits and devices that can be used in wireless communications systems that take up less space, operate more efficiently, and adapt to changing environements.For more information, see:
- S. Guo, B. J. Lei, W. Hu, W. A. Shiroma, and A. T. Ohta, “A tunable low-pass filter using a liquid-metal reconfigurable periodic defected ground structure,” Proceedings of the International Micro-wave Symposium (IMS), June 2012.
- B. J. Lei, W. Hu, A. T. Ohta, and W. A. Shiroma, “A liquid-metal
reconfigurable double-stub tuner,” Proceedings of the International
Microwave Symposium (IMS), June 2012.
- B. J. Lei, A. Zamora, T. F. Chun, A. T. Ohta, and W. A. Shiroma, "A wideband, pressure-driven, liquid-tunable frequency selective surface," IEEE Microwave and Wireless Components Letters, vol. 21, pp. 465-467, 2011.