摘要 |
A two-dimensional sensor is described including a substrate having a Si layer, a SiO2 layer and a Si3N4 layer. On the surface of the Si back side, a thin film is formed by vapor deposition for making an effect electrode. On the surface of the Si3N4 front side, a fence is attached for containing a sample cell, culture medium and a reference electrode. This sensor is placed in an incubator and a bias voltage is applied between the effect and reference electrodes. When a high frequency modulated laser beam irradiates a spot on the back side of the sensor substrate, a signal of AC photocurrent is obtained from the effect electrode. This signal corresponds to a potential alteration due to the cell activity substantially at the spot. The signal is processed in a computer. Therefore, the beam spot size and location, corresponding to the size and the location of the measurement electrode, can be adjusted easily by focusing or moving the laser beam.
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