Long-term neural recordings using MEMS based movable microelectrodes in the brain

Nathan Jackson, Arati Sridharan, Sindhu Anand, Michael Baker, Murat Okandan, Jitendran Muthuswamy

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

One of the critical requirements of the emerging class of neural prosthetic devices is to maintain good quality neural recordings over long time periods. We report here a novel MEMS (Micro Electro Mechanical Systems) based technology that can move microelectrodes in the event of deterioration in neural signal to sample a new set of neurons. Microscale electro-thermal actuators are used to controllably move microelectrodes post-implantation in steps of approximately 9 μm. In this study, a total of 12 movable microelectrode chips were individually implanted in adult rats. Two of the twelve movable microelectrode chips were not moved over a period of 3 weeks and were treated as control experiments. During the first 3 weeks of implantation, moving the microelectrodes led to an improvement in the average signal to noise ratio (SNR) from 14.61 ± 5.21 dB before movement to 18.13 ± 4.99 dB after movement across all microelectrodes and all days. However, the average root-mean-square values of noise amplitudes were similar at 2.98 ± 1.22 μV and 3.01 ± 1.16 μV before and after microelectrode movement. Beyond 3 weeks, the primary observed failure mode was biological rejection of the PMMA (dental cement) based skull mount resulting in the device loosening and eventually falling from the skull. Additionally, the average SNR for functioning devices beyond 3 weeks was 11.88 ± 2.02 dB before microelectrode movement and was significantly different (p < 0.01) from the average SNR of 13.34 ± 0.919 dB after movement. The results of this study demonstrate that MEMS based technologies can move microelectrodes in rodent brains in long-term experiments resulting in improvements in signal quality. Further improvements in packaging and surgical techniques will potentially enable movable microelectrodes to record cortical neuronal activity in chronic experiments.

Original languageEnglish (US)
Article number10
JournalFrontiers in Neuroengineering
Volume3
Issue numberJUN
DOIs
Publication statusPublished - Jun 18 2010

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Keywords

  • Brain machine interface
  • Chronic brain implant
  • Neural interface
  • Neural prostheses
  • Neural prosthesis
  • Neuronal recordings
  • Polysilicon
  • Single unit activity

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biophysics
  • Neuroscience (miscellaneous)

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