Method for testing retinal implant

A method for testing a retinal implant, comprising:

• providing an implantable device for interfacing with retinal cells, wherein the implantable device comprises at least one pixel unit and a conversion unit connected to the at least one pixel unit;
• providing an external stimulus for the at least one pixel unit to respond and output a current, the current being converted into an output voltage by the conversion unit;
• transmitting, by the implantable device, a first pulse to a processing device through a wireless interface;
• adjusting, by the conversion unit, a square wave to make a chopping switch of the conversion unit performed periodically on and off;
• decreasing, by the conversion unit, the output voltage gradually;
• transmitting, by the implantable device, a signal, which is different from the first pulse, to the processing device through the wireless interface when the output voltage is lower than a reference voltage;
• and
• acquiring, by the processing device, a current value of the pixel unit according to a time difference between the first pulse and the signal which are acquired from the implantable device.