Microrobots & cell manipulation


This research 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.

UH microrobot

The UH microrobot (visible in the top center of the image) was used to position these 20-μm-diameter beads to form "UH".
Videos of the microrobots in action:




For more information, see:

  • Q. Fan, W. Hu, and A. T. Ohta, "Efficient single-cell poration by microsecond laser pulses," Lab on a Chip, vol. 15, no. 2, pp. 581-588, 2015.
  • W. Hu, Q. Fan, and A. T. Ohta, "Interactive actuation of multiple optothermocapillary flow-addressed bubble microrobots," Robotics and Biomimetics, vol. 1, doi:10.1186/s40638-014-0014-3, 2014.
  • W. Hu, Q. Fan, and A. T. Ohta, "An opto-thermocapillary cell micromanipulator," Lab on a Chip, vol. 13, no. 12, pp. 2285-2291, 2013.
  • 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.
  • W. Hu, K. S. Ishii, and A. T. Ohta, "Micro-assembly using optically controlled bubble microrobots," Applied Physics Letters, vol. 99, 094103, 2011.

Single-cell patterning and assembly in 3D hydrogels


This project involves the micromanipulation, patterning, and microassembly of cells, followed by encapsulation in 3D hydrogel scaffolds. The aim is to be able to perform the bottom-up assembly of tissues and organs in vitro (outside the body, in a dish). These tissues and organs can be used to provide more realistic test models, streamlining the process of drug screening.

Single-cell array

An array of sixteen cells. The left image shows the bright-field image, and the right image shows the live cells fluorescing in green. The white bar represents a distance of 20 μm.

For more information, see:

  • W. Hu, Q. Fan, and A. T. Ohta, "An opto-thermocapillary cell micromanipulator," Lab on a Chip, vol. 13, no. 12, pp. 2285-2291, 2013.

Cell culturing devices


This research 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, 2011. doi:10.1155/2011/253989

Reconfigurable electronics using liquid metals


This research uses microfluidic tools and techniques to create tunable radio-frequency (RF) circuits and devices for use in wireless communications systems that take up less space, operate more efficiently, and adapt to changing environements.

Liquid metal

A frequency-tunable slot antenna using liquid metal.

For more information, see:

  • R. C. Gough, A. M. Morishita, J. H. Dang, W. Hu, W. A. Shiroma, and A. T. Ohta, "Continuous electrowetting of non-toxic liquid metal for RF applications," IEEE Access, vol. 2, pp. 874-882, 2014.
  • A. M. Morishita, C. K. Y. Kitamura, A. T. Ohta, and W. A. Shiroma, "Two-octave tunable liquid-metal monopole antenna," Electronics Letters, vol. 50, no. 1, pp. 19-20, 2014.
  • A. M. Morishita, C. K. Y. Kitamura, A. T. Ohta, and W. A. Shiroma, "A liquid-metal monopole array with tunable frequency, gain, and beam steering," IEEE Antennas and Wireless Propagation Letters, vol. 12, pp. 1388-1391, 2013.
  • 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.

Optically induced dielectrophoresis (optoelectronic tweezers)


Optically induced dielectrophoresis (ODEP) can be used to manipulate micro- and nano-scale particles, such as cells, carbon nanotubes, and nanowires. Dielectrophoresis is an electrokinetic force induced upon particles in a non-uniform electric field. ODEP integrates the flexibility and control of optical manipulation with the parallel manipulation and sorting capabilities of dielectrophoresis.

OET simulation

Electric field profile of a circular OET particle trap.

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.