Electrical probes for medicine in continual development
Electrical interfaces to biological tissue, whether to read out biological signals, to artificially stimulate nerves or muscles, or to deliver drugs is a long persecuted field of high interest. Many modern probes consist of a needle like shank hosting sites for recording or stimulation. The sites can be electrodes, openings of optical waveguides, chemical sensors, out- and inlets of fluid channels or structures for drug release. There are probes specialized to interface with various types of tissues such as the central nervous system (CNS) - either penetrating into the tissue or resting on the surface as electrocorticogram (ECoG), or probes for the peripheral nervous system such as the cochlea or retina, or stimulators for various muscles. The conventional architecture in use faces problems such as chronic stability, reliable insertion and tissue damage. Clinical applications gain significantly in value if implants remain functional over a patient’s lifetime. But despite recent approaches to enhance the chronic applicability of microprobes such as decreasing the geometry of the shank to a scaffold, lowering the stiffness of the probe or employing bio active coatings, many designs still suffer a host response. Therefore, there is an ongoing high interest in reducing this problem.
Remote actuation design improves efficacy and life of probe
A new approach by the researchers at the University of Michigan deploys very small satellite recording sites to locations outside the initial sheath of scar tissue to connect with neurons that are least affected. Without the need for active actuation, the novel design implements a mechanical actuator on the probe that is able to displace the sites relatively to the shank after implantation. The actuator can be triggered passively by the change of environment during implantation, for example by a chemical reaction that dissolves an adhesive layer, propelled by the change of pH, humidity or temperature, or it can be designed to be activated and controlled electrically or mechanically, from outside. The actuator either transduces mechanical work from energy added externally or harvested from the environment. The novel design can help to improve chronic stability of the implant, make implantation more reliable and allow integration of fine, easily breakable features, or allow interfacing tissue that remained least affected by implantation.
- Neurostimulation devices
- Brain-machine interfaces that can enable new implantable prostheses for functional motor control, the visually impaired, people suffering loss of hearing
- Chronic use of probes/penetrating layers of protective issue/protecting fine features of the probe
- Interfacing undisrupted neuronal networks
- Shank can be made robust and quality of interface less impaired