A Light-Tolerant Wireless Neural Recording IC for Motor Prediction With Near-Infrared-Based Power and Data Telemetry.

Miniaturized and wireless near-infrared (NIR) based neural recorders with optical powering and data telemetry have been introduced as a promising approach for safe long-term monitoring with the smallest physical dimension among state-of-the-art standalone recorders. However, a main challenge for the NIR based neural recording ICs is to maintain robust operation in the presence of light-induced parasitic short circuit current from junction diodes. This is especially true when the signal currents are kept small to reduce power consumption.

A Light Tolerant Neural Recording IC for Near-Infrared-Powered Free Floating Motes.

A key challenge for near-infrared (NIR) powered neural recording ICs is to maintain robust operation in the presence of parasitic short circuit current from junction diodes when exposed to light. This is especially so when intentional currents are kept small to reduce power consumption. We present a neural recording IC that is tolerant up to 300 μW/mm light exposure (above tissue limit) and consumes 0.

Bridging the"Last Millimeter" Gap of Brain-Machine Interfaces via Near-Infrared Wireless Power Transfer and Data Communications.

Arrays of floating neural sensors with high channel count that cover an area of square centimeters and larger would be transformative for neural engineering and brain-machine interfaces. Meeting the power and wireless data communications requirements within the size constraints for each neural sensor has been elusive due to the need to incorporate sensing, computing, communications, and power functionality in a package of approximately 100 micrometers on a side. In this work, we demonstrate a near infrared optical power and data communication link for a neural recording system that satisfies size requirements to achieve dense arrays and power requirements to prevent tissue heating.

Dual-Junction GaAs Photovoltaics for Low Irradiance Wireless Power Transfer in Submillimeter-Scale Sensor Nodes.

Dual-junction GaAs photovoltaic (PV) cells and modules at sub millimeter scale are demonstrated for efficient wireless power transfer for Internet of Things (IoT) and bio-implantable applications under low-flux illumination. The dual-junction approach meets demanding requirements for these applications by increasing the output voltage per cell with reduced area losses from isolation and interconnects. A single PV cell (150 μm × 150 μm) based on the dual-junction design demonstrates power conversion efficiency above 22% with greater than 1.

High-Efficiency Photovoltaic Modules on a Chip for Millimeter-Scale Energy Harvesting.

Photovoltaic modules at the mm-scale are demonstrated in this work to power wirelessly interconnected mm-scale sensor systems operating under low flux conditions, enabling applications in the Internet of Things and biological sensors. Module efficiency is found to be limited by perimeter recombination for individual cells, and shunt leakage for the series-connected module configuration. We utilize GaAs and AlGaAs junction barrier isolation between interconnected cells to dramatically reduce shunt leakage current.

Infrared Energy Harvesting in Millimeter-Scale GaAs Photovoltaics.

The design and characterization of mm-scale GaAs photovoltaic cells are presented and demonstrate highly efficient energy harvesting in the near infrared. Device performance is improved dramatically by optimization of the device structure for the near-infrared spectral region and improving surface and sidewall passivation with ammonium sulfide treatment and subsequent silicon nitride deposition. The power conversion efficiency of a 6.

Subcutaneous Photovoltaic Infrared Energy Harvesting for Bio-Implantable Devices.

Wireless biomedical implantable devices on the mm-scale enable a wide range of applications for human health, safety, and identification, though energy harvesting and power generation are still looming challenges that impede their widespread application. Energy scavenging approaches to power biomedical implants have included thermal [1-3], kinetic [4-6], radio-frequency [7-11] and radiative sources [12-14]. However, the achievement of efficient energy scavenging for biomedical implants at the mm-scale has been elusive.

Energy Harvesting for GaAs Photovoltaics Under Low-Flux Indoor Lighting Conditions.

GaAs photovoltaics are promising candidates for indoor energy harvesting to power small-scale (≈1 mm) electronics. This application has stringent requirements on dark current, recombination, and shunt leakage paths due to low-light conditions and small device dimensions. The power conversion efficiency and the limiting mechanisms in GaAs photovoltaic cells under indoor lighting conditions are studied experimentally.

Small-area Si Photovoltaics for Low-Flux Infrared Energy Harvesting.

Silicon photovoltaics are prospective candidates to power mm-scale implantable devices. These applications require excellent performance for small-area cells under low-flux illumination condition, which is not commonly achieved for silicon cells due to shunt leakage and recombination losses. Small area (1-10 mm) silicon photovoltaic cells are studied in this work, where performance improvements are demonstrated using a surface n-type doped emitter and SiN passivation.