Sympathetic nervous signal sensing system and method

A sympathetic nervous signal sensing system, comprising:

• an electrode pair disposed outside a sympathetic nervous signal source of a target, wherein the electrode pair includes:
• a first electrode configured to receive a first signal;
• and
• a second electrode configured to receive a second signal;
• a high input impedance receiving circuit coupled to the electrode pair, wherein the high input impedance receiving circuit includes:
• a first follower configured to receive the first signal and output a third signal approximately equal to the first signal;
• and
• a second follower configured to receive the second signal and output a fourth signal approximately equal to the second signal;
• a differential circuit coupled to the high input impedance receiving circuit, wherein the differential circuit is configured to perform a differential process on the third signal and the fourth signal to generate a fifth signal;
• and
• a post-processing circuit coupled to the high input impedance receiving circuit, wherein the post-processing circuit is configured to filter the fifth signal with a first filtering band to output a sympathetic nervous signal.