Cell potential measuring electrode and measuring apparatus using the same

Abstract

This invention relates to a low impedance cell potential measuring electrode assembly typically having a number of microelectrodes on an insulating substrate and having a wall enclosing the region including the microelectrodes. The device is capable of measuring electrophysiological activities of a monitored sample using the microelectrodes while cultivating those cells or tissues in the in the region of the microelectrodes. The invention utilizes independent reference electrodes to lower the impedance of the overall system and to therefore lower the noise often inherent in the measured data. Optimally the microelectrodes are enclosed by a physical wall used for controlling the atmosphere around the monitored sample.

Description

FIELD OF THE INVENTIONThis invention relates to a low impedance cell potential measuring electrode assembly typically having a number of microelectrodes on an insulating substrate and having a wall enclosing the region including the microelectrodes. The device is capable of measuring electrophysiological activities of a monitored sample using the microelectrodes while cultivating those cells or tissues in the in the region of the microelectrodes. The invention utilizes independent reference electrodes to lower the impedance of the overall system and to therefore lower the noise often inherent in the measured data. Optimally the microelectrodes are enclosed by a physical wall used for controlling the atmosphere around the monitored sample.BACKGROUND OF THE INVENTIONCell potential measuring apparatus have been developed to measure the activity or electrical potential generated by activity of nerve cells, other cells, or tissues (for example, Japanese Kokai 8-62209) without inserting g...

AI Technical Summary

Benefits of technology

According to this invention, since exclusive reference electrodes are provided at plural positions distant from the region of plural measurement microelectrodes, it is easy to place the segment of cell sample to cover all microelectrodes while not contacting with the reference electrodes. The reference electrode would typically have, for example, a larger area than a measurement microelectrodes and hence is smaller in impedance. Therefore the noise level is small even if connected to plural reference potentials for measuring positions. Therefore, common reference electrodes can be used with multiple measurement microelectrodes. Moreover, since each one of the plural reference electrodes is responsible for multiple measurement microelectrodes, the cell potentials may be easily measured simultaneously using all of microelectrodes.

Preferably the microelectrodes and the reference electrodes are formed from the same material to both simplify the manufacturing process and obtain a cost benefit. Preferably, the microelectrodes and the reference electrodes are formed of layers of nickel plating, gold plating, and platinum black on an indium-tin oxide (ITO) film. After platinization, the impedance of the reference electrodes is preferably between 2 and 3 kilohms.

Problems solved by technology

Measurement of cell potential by inserting a glass electrode or the like into the cell may damage that cell.

Long term measurement of cell potential is quite difficult.

It is further difficult to measure plural positions simultaneously; there is a limit to the number of electrodes one can place in a measurement electrode array and it is similarly difficult to adequately determine the position of the sample over measurement electrodes.

However, when measuring very low level or micro-potentials such as cell potentials, noise is a problem.

As mentioned above, when using one microelectrode as a reference electrode, simultaneous measurement of potential at 63 positions by using the remaining 63 microelectrodes is impossible because of the high noise level.

However, even when seven measuring electrodes are used with one reference electrode, the noise is still quite large.

It is quite difficult to detect a small change in cell potential from the noise.

Such a placement requires skill and is difficult because the segment S must be held by tweezers and moved while observing the segment through a microscope.

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