Electric and Magnetic Manipulation of Biological Systems
H. Lee, T.P. Hunt, Y. Liu, D. Ham and R.M. Westervelt
Department of Physics and Division of Engineering and Applied Sciences
Harvard University, Cambridge, Massachusetts 02138
Abstract. New types of biological cell manipulation systems, a micropost matrix, a microelectromagnet matrix, and a
microcoil array, were developed. The micropost matrix consists of post-shaped electrodes embedded in an insulating
layer. With a separate ac voltage applied to each electrode, the micropost matrix generates dielectrophoretic force to trap
and move individual biological cells. The microelectromagnet matrix consists of two arrays of straight wires aligned
perpendicular to each other, that are covered with insulating layers. By independently controlling the current in each
wire, the microelectromagnet matrix creates versatile magnetic fields to manipulate individual biological cells attached
to magnetic beads. The microcoil array is a set of coils implemented in a foundry using a standard silicon fabrication
technology. Current sources to the coils, and control circuits are integrated on a single chip, making the device self-
contained. Versatile manipulation of biological cells was demonstrated using these devices by generating optimized
electric or magnetic field patterns. A single yeast cell was trapped and positioned with microscopic resolution, and
multiple yeast cells were trapped and independently moved along the separate paths for cell-sorting.
INTRODUCTION
The capability to manipulate individual biological
cells in microfluidic systems is in ever-increasing
demand for biological research and clinical practices.
By combining microelectronics and microfluidics, we
have developed programmable cell manipulation
systems, a micropost matrix, a microelectromagnet
matrix, and a microcoil array, that produce versatile
electric or magnetic fields for cell manipulation.
ELECTRIC MANIPULATION
A micropost matrix generates local electric fields to
c