In this paper, we present a wireless RF-powering electronics system approach for batteryless implantable biomedical microsystem with versatile sensors/actuators on laboratory animals toward diagnosis and therapy applications. Miniaturized spiral coils as a wireless power module with low-dropout (LDO) linear regulator circuit convert RF signal into DC voltage, provide a batteryless implantation for truly free-behavior monitoring without wire dragging. Presented design achieves low quiescent-current and Line/Load Regulation, high antenna/current efficiency with safety considerations including temperature and electromagnetic absorption issues to avoid damage to the implanted target volume of tissue. Related system performance measurements have been successfully completed to demonstrate the wireless powering capabilities in desired implantable microsystems. (c) 2012 Elsevier Ltd. All rights reserved.