Patent US 10,401,396

A method of detecting a relatively weak signal includes providing an oscillatory loop that can sustain oscillations, wherein the oscillatory loop has no more than one or an even-number of stages. The loop includes a first weakly bistable differential amplifier and a second weakly bistable differential amplifier. At least one of the first and second weakly bistable differential amplifiers is connected to a behavior perturbing coupling which is operative to introduce into the connected-to amplifier a behavior tipping signal where, even if the behavior tipping signal is much weaker than an oscillation of the one or multistage oscillatory loop, the relatively weak behavior tipping signal can nonetheless alter the oscillatory behavior of the multistage oscillatory loop in a distinguishable way. The system may be used for detecting outside a patient's body weak manifestations of internal nerve firings.