The present invention relates to a microelectronics element, such as an optical receiver element, for a medical implant device to be implanted in the human or animal body, particularly for a retinal implant device. The microelectronics element comprises a functional unit including application specific microelectronics, such as a photodiode, for performing a function in the medical implant device, and rectifier means adapted for converting an AC supply voltage into a DC voltage. The DC voltage provided by the rectifier means, or an operating voltage derived from the DC voltage, is configured to be supplied to the functional unit. Further, the functional unit and the rectifier means are integrated on a common semiconductor substrate and configured such that the rectifier means isolates the microelectronics element from application of an external DC supply voltage. The invention also relates to a medical implant device, such as a retinal implant, which incorporates such a microelectronics element.