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.

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 kΩ to 95 µA and load impedances from 30 kΩ to 70 kΩ, 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.

Responsive neuromodulation is increasingly being used to treat patients with neuropsychiatric diseases. Yet, inefficient bridges between traditional and new materials and technological innovations impede advancements in neurostimulation tools. Signaling in the brain is accomplished predominantly by ion flux rather than the movement of electrons. However, the status quo for the acquisition of neural signals is using materials, such as noble metals, that can only interact with electrons. As a result, ions accumulate at the biotic/abiotic interface, creating a double-layer capacitance that increases impedance and negatively impacts the efficiency of neural interrogation. Alternative materials, such as conducting polymers, allow ion penetration in the matrix, creating a volumetric capacitor (two orders of magnitude larger than an area-dependent capacitor) that lowers the impedance and increases the spatiotemporal resolution of the recording/stimulation. On the other hand, the increased development and integration capabilities of CMOS-based back-end electronics have enabled the creation of increasingly powerful and energy-efficient microchips. These include stimulation and recording systems-on-a-chip (SoCs) with up to tens of thousands of channels, fully integrated circuitry for stimulation, signal conditioning, digitation, wireless power and data telemetry, and on-chip signal processing. Here, we aim to compile information on the best component for each building block and try to strengthen the vision that bridges the gap among various materials and technologies in an effort to advance neurostimulation tools and promote a solution-centric way of considering their complex problems.