Power efficiency is critical for enabling the long-term use of implantable and wearable ultrasound (US) neuromodulation systems, where excessive power consumption leads to thermal dissipation and frequent battery replacement. Conventional therapeutic phased arrays typically generate equal pressures from all elements, not taking into account the directivity of each element, and thus the different source contributions to the focal spot, leading to power inefficiency. Although prior methods allow control of source pressure at the element level, such as driver supply control, duty cycle adjustment, or deterministic pulse skipping, they either require complex circuitry, introduce dynamic switching losses, or cause undesirable temporal fluctuations in focal pressure, respectively. To address these limitations, we introduce a novel driving scheme that explores pseud-random pulse skipping to control element-level source pressure and thus optimize power consumption in 2D phased array ultrasound transmitters. The pseudo-random pulse skipping approach allows for regulating the source pressure in each element while preserving a stable pressure at the focal spot, which is required for therapeutic applications. The driving scheme for a single element was implemented in an ASIC, and the result shows that by having different percentages of pulse skipping, we can also modulate the power consumption of the driving channel.

Ultrasound (US) technology has emerged as a powerful modality in both medical imaging and therapy, offering non-invasive, real-time, and high-resolution capabilities. Conventional dual-mode systems employ separate US transducers for imaging and therapy, each mechanically configured during fabrication for a fixed quality factor (Q-factor) through the presence of a backing layer or air-based backing layer, respectively. This approach increases system cost, physical footprint, power consumption, and integration complexity while preventing seamless real-time switching between modes. A novel electronically configurable Q-factor control circuit architecture for a single set of 2D phased-array piezoelectric transducers is proposed in this work. The proposed method employs an active damping compensation technique to electronically reduce the Q-factor during imaging mode while preserving the high-Q state for the therapeutic mode, eliminating the need for mechanical reconfiguration. System and circuit-level simulations in TSMC 180 nm BCD technology using a PZT-5A air-backed transducer BVD model demonstrate a reduction in the Q-factor from 78.3 to 8.08 with fewer than 1% variation across PVT corners. These results place the Q-factor achieved in the imaging mode within the optimal range for high-resolution ultrasound imaging, while maintaining high-Q performance for the therapeutic mode.

Developing an implantable/wearable 2D ultrasound phased array for ultrasound neuromodulation poses several challenges, including power requirements for driving the piezoelectric transducers to generate sufficient pressure at the focal spot. Therefore, minimizing power consumption is crucial to minimize excessive thermal dissipation and to ensure long-term usability without frequent charging or battery replacement. Prior work has improved efficiency based on transducer fabrication and circuit design optimizations. To further address this issue, we propose a new approach to minimize power consumption by tailoring the driving amplitude of each element in a 2D phased array based on their individual contribution to the focal spot pressure.

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.