Abstract of the INTER project
The aim of the INTER project is to investigate fundamental issues related to the development of a new generation of implantable neural microsystems, which give access to a large portion of the information bandwidth of the nervous system. A few neural microsystems, comprising guidance channels, "via holes" dices and an on-chip integrated preprocessing circuitry, will be designed, fabricated and tested in combination with an external neural network-based controller.
The INTER system will establish bidirectional electrical communication between the nervous system and external processing devices, and will allow to pick-up signals from motor axons and to stimulate sensory axons. This opportunity will open new avenues for research in neurophysiology, for implementing new limb and sensory prostheses, and for functional neuromuscular stimulation.
A short introduction to the INTER project
The aim of the INTER project (Intelligent Neural InTERface) is to investigate fundamental issues related to the design and fabrication of a new generation of microsystems applicable as neural prostheses. A global overview for a PNS-remoted limb prostheses is shown in figure 1.
Nerve signals will be recorded and amplified by a neurosensor. The neurosensor is a regeneration-type sensor. The principle of the neurosensor is explained below. The signal will be processed by an artificial neural net (ANN). Via a control unit the prostheses will be remoted. Ideally, the prostheses is equipped with sensors. Signals from the sensors will be processed by an ANN and transmitted via a signal generator and the neurosensor to the peripheral nervous system (PNS). This means, the prostheses will be completely controlled from the PNS like a natural limb.
The principle of the implementation and the neurosensor which will be used in the INTER-project is shown in figure 2.
Peripheral nerves of vertebrates will regenerate if severed. For this reason, the peripheral nerve can be surgically severed in order to insert the proximal and the distal stump into the guidance channel. The guidance channel encloses the chip. The main functions of the guidance channel are to provide a stable physical connection between the chip and the stumps of the nerve, and to promote nerve generation and guide axons growth from the proximal nerve stump towards the distal nerve stump. The chip is fabricated on a silicon substrate perforated by multiple 'via holes'. The axons regenerate through the via holes from the proximal stump towards the distal stump of the nerve. Nerve signals can be recorded by electrodes, which are enclosing some of the via holes. An on-chip circuitry amplifies and preprocesses the nerve signals. The amplified signals are transferred to the units which are controlling the prostheses as shown in figure 1.
A prototype of a regeneration-type neurosensor, which will be used in the INTER-project, has been designed by Meier et al. at Fraunhofer Institut, and is shown in figure 3.
INTER - Intelligent Neural inTERface: Signalprocessing
The signal processing can be performed in realtime using Kohonen's self-organizing map (SOM), an artficial neural net (ANN).
The partners of the INTER project