This Project aims to provide enabling microelectronic technologies for the integration and miniaturization of a smart neural stimulation system based on optogenetics, which serves as experimental vehicle for the development of new procedures in neurobiology and, ultimately, for the implementation of new neural prosthesis, more focus and secure than those currently available, for the treatment of different pathologies of the nervous system (severe sensory deficits, brain diseases, chronic pain, and others).
Within this general scenario, our objective will be to provide the basis towards a reliable and efficient closed-loop mechanism which, based on the electrical activity recorded from the genetically encoded cells, is able to provide an efficient and non-harmful actuation by optic means. This real-time feedback procedure will support the adaptability of the system to the plasticity of the neural tissue and, thereby, it will open up doors for the implementation of robust, long lifetime neural prosthesis whose operation self-adjusts to the patient's progress.
The system to be developed will be scalable and reconfigurable with the number of recording electrodes and optical stimulation sources (it might be regarded as a MIMO -multi-input, multi-output- control system) and will allow the activation of LEOs incorporated into the probe or, alternatively, the triggering of any convenient external light source by means of a custom data pathway. In the former case, LEOs may be placed in direct contact with the tissue (by using micro-LEOs integrated in the probe) or employ optical fibers for guiding photostimulation. For the sake of easy handling, data transfer to/from the complete recording/stimulation system will employ wireless techniques.
According to this concept, the system implementation will encompass the fabrication of two Application-Specific Integrated Circuits (ASICs) together with so me commercial components (essentially, a microcontroller for supervising the stimulation feedback loop and an ultra-low power wireless transceiver). One of the ASICs, denoted as stimulation ASIC, will implement the stimulation circuitry, whereas, the other ASIC, denoted as acquisition ASIC, will include circuits for recording, processing and communications, as well as a power management unit!. A multi-chip solution is preferred over a single monolithic integration in order to increase the reliability of the system, reduce the fabrication risks, and improve the performance of the neural recording channels which, otherwise, it would become adversely affected by the commutations of the stimulation circuitry.
The ASICs will be fabricated in a low-cost O.18um CMOS technology and tested either individually, or connected one to another in the final system platform. Their characterizations will consist in mixed-signal and optical tests in the premises of our laboratories. Additionally, we will lay plans on the validations of the prototypes with in vitro and in vivo measurements, to be carried out in Bioengineering Institutes with which the applicant group holds collaboration agreements.