To enhance the signal integrity of high-density neural-sensing signals, this work presents an implantable high spatial resolution μ-probe array with through-silicon via (TSV) 2.5D integration technology that realizes a miniaturized implantable device on flexible printed circuit (FPC) interposer. The proposed microsystem was composed of two 32-channel neural sensing chips and one radio frequency chip for neural signal processing. The μ-probe array can achieve better signal-to-noise ratio with neural-signal acquisition and processing circuit composed of a pseudo-resistor-based analog front-end amplifier. Moreover, a receiving antenna is also implemented on the backside of FPC for wireless data and power transmission. The feasibility of the proposed μ-probe array, Tx and Rx antenna, 32-channel neural sensing circuits in the 64-channel wireless microsystem have been successfully demonstrated for future integration and animal experiments.