Implants using ultrasonic waves for stimulating tissue

A method of stimulating a tissue, comprising:

• receiving ultrasonic waves at an implantable device configured to detect a physiological signal and emit an electrical pulse to the tissue;
• converting, at the implantable device, energy from the ultrasonic waves into an electrical current that flows through a modulation circuit;
• detecting, at the implantable device, the physiological signal;
• producing, at the implantable device, a modulated electrical current based on the detected physiological signal;
• transducing, at the implantable device, the modulated electrical current into an ultrasonic backscatter that encodes information related to the detected physiological signal;
• and
• emitting, from the implantable device, the ultrasonic backscatter that encodes the information related to the detected physiological signal;
• receiving, at an interrogator comprising one or more ultrasonic transducers, the ultrasonic backscatter that encodes the information related to the detected physiological signal;
• emitting, from the interrogator, ultrasonic waves configured to power the implantable device;
• receiving, at the implantable device, the ultrasonic waves configured to power the implantable device;
• converting, at the implantable device, energy from the ultrasonic waves configured to power the implantable device into an electrical current that charges an energy storage circuit of the implantable device;
• emitting, from the interrogator, ultrasonic waves encoding a trigger signal;
• receiving, at the implantable device, the ultrasonic waves encoding the trigger signal;
• and
• emitting, from the implantable device, an electrical pulse that stimulates the tissue in response to the trigger signal.