Neural Dielet: A 0.4 mm3 Battery-Less Crystal-Less Neural-Recording System on Die Achieving 1.6 cm Backscatter Range With 2 mm x 2 mm On-Chip Antenna

Miniaturization is essential in the design of wireless neural-recording systems. In recent years, the battery in neural-recording systems can be eliminated by wireless power transfer (WPT), while antenna and crystal become two main bottlenecks to minimize a battery-less neural implant. In conventional battery-less designs, the miniaturization of antenna led to a short communication range, and a crystal-less clock suffered from noise issue or power-hungry circuits. In this work, we demonstrate a 0.4 mm(3) neural dielet, which is a battery-less crystal-less neural-recording system on die (SoD) within a 2 mm x 2 mm on-chip coil antenna. The communication range through the ultra-small antenna is extended by a proposed dither-based 3rd-order intermodulation (IM3) technique, which prevents the backscatter communication fromWPTblocker. Meanwhile, a dither-based 2nd-order intermodulation (IM2) wireless-lock technique is proposed to remove the crystal. Measured results show that the SoD consumes 53.2 mu W power and achieves a wireless communication range of 1.6 cm at a bit-error rate (BER) of 8 x10(-6), accompanied by simultaneous WPT for battery-less operation. In the animal experiment, the neural signal wirelessly recorded by our SoD in a battery-less way matches favorably with the wire-test results obtained by a commercial chip.

Automated summary

Miniaturization is crucial for designing wireless neural-recording systems. In recent years, the elimination of batteries in these systems has been achieved through wireless power transfer (WPT), but the miniaturization of the antenna and crystal has posed challenges. This study presents a 0.4 mm³ battery-less crystal-less neural-recording system on die (SoD) with a 2 mm x 2 mm on-chip coil antenna. The communication range is extended by a proposed dither-based technique, and a wireless-lock technique is used to remove the crystal. The SoD achieves a wireless communication range of 1.6 cm with a power consumption of 53.2 mu W, accompanied by simultaneous WPT for battery-less operation.