The development of neurostimulation devices for visual and somatosensory prostheses is rapidly gaining momentum, where scaling the number of stimulation channels is crucial to improve treatment efficacy. To this end, optimizing power efficiency is critical, particularly in wirelessly powered systems. Although current-mode stimulation is generally preferred for safety reasons, it is often associated with significant power overhead losses in the output driver. This challenge becomes even more pronounced in multichannel configurations, where the required load voltage varies unpredictably across channels and over time. Compliance monitor circuits have been used to scale the output driver voltage supply, which in turn reduces losses and improves power efficiency. However, existing implementations lead to increased area and power overhead while lacking the ability to adapt rapidly to dynamic load conditions. This work presents a stimulator architecture that enables autonomous output supply scaling per channel, minimizing power dissipation across a wide range of currents and impedances without requiring explicit compliance monitoring. A two-channel prototype fabricated in 0:18 μm CMOS was validated with both linear loads and electrodes. The proposed strategy achieves outputdriver efficiencies above 80 % for stimulation currents of 30 k to 95 μA and load impedances from 30 k to 70 k, showing up to 4.3 times improvement compared to a fixed-voltage supply. Furthermore, the circuit shows rapid adaptation to changes in the required output voltage, enabling 100 μs stimulation pulses with a 1 μs inter-pulse delay. This feature allows time-division multiplexing across electrodes with varying load conditions, which could be further explored to increase the number of electrodes served per stimulation channel and thereby enhance scalability.

Accurate detection of physiological vibrations is vital for monitoring health and enabling sensory feedback in bioelectronics. Current technologies often suffer from low signal-to-noise ratios (SNR), bulkiness, and the need for external amplification. Here, we introduce piezoelectric internal ion-gated organic electrochemical transistors (Piezo-IGTs), which efficiently convert mechanical vibrations into amplified electrical signals. These devices integrate laminated P(VDF-TrFE) microfiber films as the gate atop the transistor channel, generating voltage upon deformation to modulate mobile ions in the conducting polymer. Fabricated via sequential deposition and lamination, Piezo-IGTs achieve high fill factors and efficient on-site amplification, improving SNR over standalone piezoelectric films. They operate near 0 V gate voltage, enabling low-power performance. We validate their functionality in mechanomyography, speech recognition, and mechanocardiography using microscale Piezo-IGTs. This self-contained, flexible architecture demonstrates promise for integration into implantable and wearable systems, offering real-time, high-fidelity acquisition of bio-mechanical signals in next-generation health monitoring and neuroprosthetic applications.