Abstract: An in vivo potential measurement device includes an insulating member and an amplifier. The insulating member has an electrode. The insulating member is inserted into an organ of a living body such that an outer peripheral face of the insulating member contacts with an inner wall face of the organ at a contact site. The electrode senses electric potential at the contact site. The amplifier amplifies the electric potential to obtain output voltage. The amplifier has input capacitance Cin and input resistance Rin that satisfy Cin/Ce>0.1 and 1/(2?fCeRin)>0.1, where Ce represents capacitance of the insulating member at the contact site, and f represents frequency of the electric potential at the contact site on the inner wall face. A contact state between the outer peripheral face and the inner wall face is evaluated using the output voltage.

Abstract: At least two electrodes are disposed at a predetermined interval on a living body surface, a first voltage V1 generated when a first external resistor is connected in parallel between the two electrodes, and a second voltage V2 generated when a second external resistor is connected in parallel between the two electrode are measured, a bioimpedance between the two electrodes at a muscle site under the living body surface is calculated based on a voltage ratio V1/V2 between the first voltage V1 and the second voltage V2, and local muscle fatigue at the muscle site is evaluated based on a change over time in the calculated bioimpedance.

Abstract: In an in-vivo signal source detection method, three electrodes are arranged on the circumference of a surface of an living body to surround multiple muscle fibers; a first voltage Vi generated when a first external resistor is connected to between each electrode and a ground potential and a second voltage V?i generated when a second external resistor is connected to between each electrode and the ground potential; and a ratio Vi/V?i is calculated from the first voltage Vi and the second voltage V?i, and the position of a signal source in the living body is detected based on three ratios Vi/V?i.

Abstract: An in vivo potential measurement device includes an insulating member and an amplifier. The insulating member has an electrode. The insulating member is inserted into an organ of a living body such that an outer peripheral face of the insulating member contacts with an inner wall face of the organ at a contact site. The electrode senses electric potential at the contact site. The amplifier amplifies the electric potential to obtain output voltage. The amplifier has input capacitance Cin and input resistance Rin that satisfy Cin/Ce>0.1 and 1/(2?fCeRin)>0.1, where Ce represents capacitance of the insulating member at the contact site, and f represents frequency of the electric potential at the contact site on the inner wall face. A contact state between the outer peripheral face and the inner wall face is evaluated using the output voltage.

Abstract: In an in-vivo signal source detection method, three electrodes are arranged on the circumference of a surface of an living body to surround multiple muscle fibers; a first voltage Vi generated when a first external resistor is connected to between each electrode and a ground potential and a second voltage V?i generated when a second external resistor is connected to between each electrode and the ground potential; and a ratio Vi/V?i is calculated from the first voltage Vi and the second voltage V?i, and the position of a signal source in the living body is detected based on three ratios Vi/V?i.

Abstract: A method for detecting a position of a signal source in a living body includes: arranging three electrodes on a surface of the living body and alternately connecting a first external resistance and a second external resistance in parallel between the electrodes and a ground potential; measuring first voltages Vi (i=1, 2, 3) generated at the respective electrodes when the first external resistance is connected in parallel between the electrodes and the ground potential, and second voltages Vi (i=1, 2, 3) generated at the respective electrodes when the second external resistance is connected in parallel between the electrodes and the ground potential; and calculating three ratios Vi/V?i (i=1, 2, 3) from the first and second voltages Vi and V?i, and detecting the position of the signal source in the living body based on the three ratios Vi/V?i (i=1, 2, 3).

Abstract: A method for detecting a position of a signal source in a living body includes: arranging three electrodes on a surface of the living body and alternately connecting a first external resistance and a second external resistance in parallel between the electrodes and a ground potential; measuring first voltages Vi (i=1, 2, 3) generated at the respective electrodes when the first external resistance is connected in parallel between the electrodes and the ground potential, and second voltages Vi (i=1, 2, 3) generated at the respective electrodes when the second external resistance is connected in parallel between the electrodes and the ground potential; and calculating three ratios Vi/V?i (i=1, 2, 3) from the first and second voltages Vi and V?i, and detecting the position of the signal source in the living body based on the three ratios Vi/V?i (i=1, 2, 3).