Micromachined muscle cell analysis chip

We report the fabrication of a microfluidic biochip integrated with an acoustic wave sensor that can be used to characterize the contraction of single cardiac (heart) muscle cells. The work will lead to rapid analysis of single muscle cells in response to various drugs by determining changes in mass and viscoelastic properties during cell contraction and relaxation. The microfabricated device is a combination of a top cover plate which is a glass substrate containing etched channels and a bottom plate which is an AT-cut quartz crystal with excitation electrodes. The glass plate is micromachined with a network of channels and chambers, which is intended for delivery of fluids, selection and retention of single muscle cells. The bottom plate (quartz crystal) comprises all the patterned electrodes for acoustic wave launching and detection. The quartz plate is operated in the thickness-shear acoustic wave mode. In preliminary tests, myocytes (muscle cells) were introduced into the fluidic channels through a drilled hole. A cardiac muscle cell was monitored optically using a microscope while the cell was stimulated to contract and relax by a high calcium ion concentration (bath solution). Using the impedance mode of a network/spectrum analyzer, various parameters of the AT-cut quartz crystal, which include resonant frequencies, frequencies at minimum and maximum impedance, and equivalent circuit parameters, were continuously monitored. This paper describes the device fabrication, experimental setup, procedure, and some preliminary results of the impedance analysis. Future work on deriving mass and viscoelastic parameters, monitoring their changes in response to drugs, measuring the intracellular calcium ion concentration, and prototyping an integrated hand-held unit that consists of the microfabricated chip will be discussed.