Monitoring elevated intracranial pressure (ICP) is a critical, life-saving intervention. This chapter introduces a highly compact, battery-free implantable device designed for ICP monitoring, consisting of an external power transmitter (Tx) and an internal biotelemetric receiver (Rx). Due to the ultra-small size of the implantable antenna (5.6 mm \(\times \) 6 mm \(\times \) 0.2 mm, totaling 6.72 mm \(^3\) ), the system operates in dual bands (915 MHz and 1900 MHz) to facilitate concurrent power delivery and data transmission. The implant achieves wireless power in the radiative near-field at 1900 MHz, optimizing power transfer efficiency (PTE). The device also exhibits measured peak gains of −26.8 dBi and −18.8 dBi, with impedance-matched bandwidths of 9.83% at 915 MHz and 27.9% at 1900 MHz. An analysis of wireless power transfer efficiency relative to distance revealed a maximum PTE of −25.9 dB at a 20 mm separation (0.1267 \(\lambda \) ) between the Tx and Rx. The rectifier component of the system demonstrated a peak power-conversion efficiency of 82% at an input power of 2 dBm. To assess the performance of the biotelemetric implantable system, simulations were conducted using both finite-element method (FEM) and finite-difference time-domain (FDTD) techniques. Experimental validation was carried out in a human head phantom filled with saline solution and using minced pork tissue. Results from these measurements were found to be in strong agreement with the simulation data, confirming the effectiveness of the biotelemetric system.