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 Time-Domain Analog Spatial Compressed Sensing Encoder for Multi-Channel Neural Recording.

A time-domain analog spatial compressed sensing encoder for neural recording applications is proposed. Owing to the advantage of MEMS technologies, the number of channels on a silicon neural probe array has doubled in 7.4 years, and therefore, a greater number of recording channels and higher density of front-end circuitry is required. Since neural signals such as action potential (AP) have wider signal bandwidth than that of an image sensor, a data compression technique is essentially required for arrayed neural recording systems. In this paper, compressed sensing (CS) is employed for data reduction, and a novel time-domain analog CS encoder is proposed. A simpler and lower power circuit than conventional analog or digital CS encoders can be realized by using the proposed CS encoder. A prototype of the proposed encoder was fabricated in a 180 nm 1P6M CMOS process, and it achieved an active area of 0.0342 mm 2 / ch . and an energy efficiency of 25.0 pJ / ch . · conv .

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems.

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 µm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction.