The ultimate objective of this research is to create a paradigm shift in biomedical electrode design. Rather than relying on unwieldy metal electrodes and direct charge injection, tissue engineered bioelectronics use cells embedded within devices to provide a natural mode of physiological tissue activation. These new designs provide communication, such as recording or stimulation, through formation of functional synapses between devices and cells. This revolutionary approach provides a safer mechanism for neural cell stimulation, which is more compatible with neural cell survival and regeneration. It will also support development of more complex and elegant devices to restore sensory and motor functions.
To achieve optimal performance from bionic devices, an intimate connection between “hard” device and “soft” excitable tissue is required. Existing bionic implants use metal electrodes, which have a restircted ability to transfer electricity to biological tissues and poor integration with cells. This limits their use in next-generation, high resolution devices, such as the bionic eye and brain-machine interfaces. Alternate materials have been explored as coatings to improve the performance of metal electrodes, but scar tissue formation remains a problem. This research project has yielded a new approach of incorporating neural cells within a bioactive conductive hydrogel (CH) electrode to promote functional, physiological junctions between device and tissue.
To develop these "living bioelectronics" a hydrogel carrier has been engineered to provide appropriate cues that support survival and differentiation of cells into neural networks, while also enabling transfer of electricity and recording of cellular activity. The living electrode construct has been developed and it has been shown that the electrical properties of these new cell loaded materials are significantly better than traditional metals, such as platinum, indicating that this construct can be used to drive devices at lower power. It is proposed that this structure can address the need for such intimate communication between device and cells and can be safely used in micro-scale implantable devices. Neural cells and supporting glia have been encapsulated within the electrode materials and shown to both differentiate and be capable of forming active neural networks that have instrinic electroactivity and respond to electrical stimulation.
Ultimately, it is expected that functional cells that are embedded in bionic devces will effectively support an integrated interface with indistinct borders between synthetic devices and the surrounding tissue. This type of construct can be used to create not only direct connections to neural tissues, but also neuro-muscular junctions (NMJ) to record cell activity and drive peripheral prosthetics or rehabilitating limbs (via functional electrical stimulation, FES). Living bioelectronics have application across a wide range of medical implants, including robotic peripheral limb prostheses, cochlear implants, deep brain stimulators, cardiac pacemakers and other medical electrodes.
3. Additional Details
Papers we have published on this topic:
- Aregueta-Robles UA, Lim KS, Martens PJ, Lovell NH, Poole-Warren LA, Green RA. “Producing 3D Neuronal Networks in Hydrogels for Living Bionic Device Interfaces” 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Milan, Italy, 4pp, 2015.
- Green RA, Lim KS, Henderson WC, Hassarati RT, Martens PJ, Poole-Warren LA, Lovell NH. “Living electrodes: Tissue engineering the neural interface”, Proceedings of the 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Osaka, Japan, 4pp, 2013.
- Patton AJ, Amella AD, Martens PJ, Lovell NH, Poole-Warren LA, Green RA (invited speaker). “Freestanding, soft bioelectronics” Proceedings of the 7th International IEEE EMBS Conference on Neural Engineering, Montpellier, France, 4pp, Accepted for publication 2015
- Aregueta-Robles UA, Woolley AJ, Poole-Warren LA, Lovell NH, Green RA, “Organic electrode coatings for next-generation neural interfaces” Frontiers in Neuroengineering, 7(15), 1-18, 2014.
- Hassarati RT, Dueck WF, Tasche C, Carter P, Poole-Warren LA, Green RA, “Improving cochlear implant properties through conductive hydrogel coatings,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, 22(2) 411-418, 2014.
- Cheong GLM, Lim KS, Jakubowicz A, Martens PJ, Poole-Warren LA, Green RA. “Conductive hydrogels with tailored bioactivity for implantable electrode coatings”, Acta Biomaterialia,10(3), 1216-1226, 2014.
Links to more information on my research: