Completed Project (2010-2014)

Research Team: Song Luan (PhD thesis), Timothy Constandinou
Collaborator: Andrew Jackson (Institute of Neuroscience, Newcastle University)
Funding: Engineering and Physical Sciences Research Council (EPSRC) EP/I000569/1

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Intraspinal Microstimulation (ISMS) is an emerging technique used by neuroscientists to directly stimulate motor neurons in the spinal cord. It holds the promise of recruiting better co-ordinated and less fatigue-prone muscle movements with lower stimualtion energy than the traditional direct electrical muscle stimulation. However, most of the methods for ISMS today are using wires which not only limits the movement of the implantee but also bears the risk of infection. Hence, this project investigated the integration of wireless technology and ISMS.

Outcomes

A new safe and efficient stimulation mode which delivers the stimulus in charge packets has been developed and tested. The test chip has been fabricated using a standard 0.18μm CMOS process without requiring a high voltage module. It has been tested using an RC load to emulate the electrode-tissue interface and also ex-vivo on a xenopus laevis sciatic nerve using a cuff electrode interface. Both the power consumption and charge balancing capability are comparable to the state of the art. Furthermore, an 8-channel multi stimulation mode system has been designed and tested. This is the first chip-based platform to enable constant voltage, constant current and charge (the new method) stimulation modes, mono/bi/multi-polar stimulation, and a programmable stimulus waveform. All functionality has been tested both with a passive RC load and PNS electrodes. The system includes a onboard system controller that provides commands and data via a single serial link. This makes the system suitable for future integration with a wireless biotelemetry.

Publications

2014

• Luan, S., & Constandinou, T. G. (2014). A charge-metering method for voltage-mode neural stimulation. Journal of neuroscience methods, 224, 39-47.
• Luan, S., Williams, I., Nikolic, K., & Constandinou, T. G. (2014). Neuromodulation: present and emerging methods. Frontiers in neuroengineering, 7.

2013

• Leene, L. B., Luan, S., & Constandinou, T. G. (2013). A 890fJ/bit UWB transmitter for SOC integration in high bit-rate transcutaneous bio-implants. In Circuits and Systems (ISCAS), 2013 IEEE International Symposium on (pp. 2271-2274).

2012

• Guilvard, A., Eftekhar, A., Luan, S., Toumazou, C., & Constandinou, T. G. (2012). A fully-programmable neural interface for multi-polar, multi-channel stimulation strategies. In Circuits and Systems (ISCAS), 2012 IEEE International Symposium on (pp. 2235-2238).
• Luan, S., & Constandinou, T. G. (2012, May). A novel charge-metering method for voltage mode neural stimulation. In Circuits and Systems (ISCAS), 2012 IEEE International Symposium on (pp. 2239-2242).
• Mirza, K. B., Luan, S., Eftekhar, A., & Constandinou, T. G. (2012). Towards a fully-integrated solution for capacitor-based neural stimulation. In Circuits and Systems (ISCAS), 2012 IEEE International Symposium on (pp. 2243-2246).

2011

• Luan, S., Eftekhar, A., Murphy, O. H., & Constandinou, T. G. (2011). Towards an inductively coupled power/data link for bondpad-less silicon chips. In Circuits and Systems (ISCAS), 2011 IEEE International Symposium on (pp. 2597-2600).