(H-313) Highly Sensitive Battery-less and Wireless Neural Recorder with Additive Manufacturing

Introduction: Neural recording is critical to understanding our brain’s functionalities, and this is done using wireless implants. However, existing wireless implants require batteries or energy harvesting modules that induce heat and can cause tissue damage. To overcome these issues, a battery-less wireless neurosensing system (WiNS, Fig. 1A) has been proposed [1]. With its minimal heating, this new implant can minimize injury and preserve the patients’ natural lifestyle. Recently, WiNS has been enhanced with an impedance matching circuit between electrodes and the recording circuits [2]. However, the added components caused some loss of sensitivity and increased the size of the recorder. To improve on the latter, we propose a novel design and fabrication methodology using 3D additive manufacturing of the recorder.

Materials and Methods: WiNS is comprised of an implanted neuropotential recorder and an exterior interrogator. For recording, the interrogator sends a carrier excitation that is mixed with the neural signals captured by the recorder. This modulated signal is then sent back to the interrogator for posterior demodulation and extraction of the neural signals. The fabrication of our proposed recorder employs additive manufacturing leading to a recorder size reduction of 52% as compared to previous designs [2]. The implanted sensor was also coated with PDMS polymer for biocompatibility.

Results, Conclusions, and Discussions: Fig. 1B shows the recorder’s transmission coefficient (S₂₁) demonstrating less than 3 dB discrepancy in the two bands of interest. Fig. 1C shows the benchtop set up and power received at 4.8𝐺𝐻𝑧 ± 𝑓_{𝑛𝑒𝑢𝑟𝑜}. We remark that the measurements indicate a detectable neural signal of amplitude as low as 20 µV_pp, a 10-fold improvement in sensitivity [2].

In conclusion, we proposed a novel 3D additive sensor package that is wireless, battery-less and matched to high impedance commercial electrodes. The implant size has been reduced by 52% and the sensitivity has been improved 10-fold. Future work will focus on 1) multichannel recording and on adding demodulation circuits in the packaged system, 2) in vivo testing in pigs.

These results demonstrate the potential of WiNS which can significantly impact the future neuroscience research. The battery-less and wireless recorded data could be employed to analyze the patient’s well-being in real-time as well as offer a diagnosis and treatment for several neurological disorders such as epilepsy, Parkinson’s, Alzheimer’s, tremor, etc.


Acknowledgements (Optional): This work was supported by National Science Foundation award 2052764 and the Nano Dimension Co. The device 3D fabrication was done by the Nano Dimension Co.


References (Optional): : [1] C. W. L. Lee, A. Kiourti, and J. L. Volakis, “Miniaturized Fully Passive Brain Implant for Wireless Neuropotential Acquisition,” IEEE Antennas Wirel. Propag. Lett., vol. 16, pp. 645–648, 2017, doi: 10.1109/LAWP.2016.2594590.

[2] W. C. Chen, K. Guido, and A. Kiourti, “Passive impedance matching for implanted brain-electrode interfaces,” IEEE J. Electromagn. RF Microwaves Med. Biol., vol. 3, no. 4, pp. 233–239, 2019, doi: 10.1109/JERM.2019.2904024.