We developed a biomagnetic measurement system on mice. Our initial model of the system has the magnetic field sensitivity of 1.3 pT/Hz1/2 in the white-noise region (10 Hz-10 kHz). And using the system, we succeeded to obtain magnetically the heart activity on mice. However, in its application to measure the brain activity on mice, it was necessary to improve the magnetic field sensitivity of the system. Therefore, we changed the material of the window cap, which holds a sapphire glass window on the dewar tail, to ceramic. The system noise was decreased and the magnetic field sensitivity of the system was improved to 0.75 pT/Hz1/2 in the white-noise region. For an initial measurement of the brain activity, we also developed a whisker stimulation system using a piezoelectric element to evoke somatosensory responses.
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