A wearable platform for closed-loop stimulation and recording of single-neuron and local field potential activity in freely moving humans.

Advances in technologies that can record and stimulate deep brain activity in humans have led to impactful discoveries within the field of neuroscience and contributed to the development of novel therapies for neurological and psychiatric disorders. Further progress, however, has been hindered by device limitations in that recording of single-neuron activity during freely moving behaviors in humans has not been possible. Additionally, implantable neurostimulation devices, currently approved for human use, have limited stimulation programmability and restricted full-duplex bidirectional capability. In this study, we developed a wearable bidirectional closed-loop neuromodulation system (Neuro-stack) and used it to record single-neuron and local field potential activity during stationary and ambulatory behavior in humans. Together with a highly flexible and customizable stimulation capability, the Neuro-stack provides an opportunity to investigate the neurophysiological basis of disease, develop improved responsive neuromodulation therapies, explore brain function during naturalistic behaviors in humans and, consequently, bridge decades of neuroscientific findings across species.

A 0.338 cm3, Artifact-Free, 64-Contact Neuromodulation Platform for Simultaneous Stimulation and Sensing.

Neuromodulation (NM) is the alteration of nervous tissue function through targeted delivery of a stimulus, such as electrical stimulation, into the affected neurological sites in the body. We present a bidirectional NM interface that features 100 mVpp linear input range and ability to sense data concurrent with stimulation (without blanking). The system includes a flexible 8-driver-to-64-contact custom waveform stimulator able to deliver up to 5.1 mA per driver and a 64-contact sensing unit with online blind artifact rejection unit. This artifact rejection unit removes stimulation artifacts from recorded data and allows extraction of neural biomarkers. The NM interface also features an efficient, integrated power management unit that can support various power delivery options. The proposed 64-contact interface satisfies design requirements of human-grade brain implants at unprecedented level of electronic miniaturization compared to state-of-the-art.

A Miniaturized 0.78-mW/cm2 Autonomous Thermoelectric Energy-Harvesting Platform for Biomedical Sensors.

In order to use thermoelectric energy harvesters (TEHs) as a truly autonomous energy source for size-limited sensing applications, it is essential to improve the power conversion efficiency and energy density. This study presents a thin-film, array-based TEH with a surface area of 0.83 cm2. The TEH autonomously supplies a power management IC fabricated in a 65-nm CMOS technology. The IC utilizes a single-inductor topology with integrated analog maximum power point tracking (MPPT), resulting in a 68% peak end-to-end efficiency (92% converter efficiency) and less than 20-ms MPPT. In an in-vivo test, a 645-µW regulated output power (effective 3.5 K of temperature gradient) was harvested from a rat implanted with our TEH, demonstrating true energy independence in a real environment while showing a 7.9 × improvement in regulated power density compared to the state-of-the-art. The system showed autonomous operation down to 65-mV TEH input.