Background
Neural electrical stimulation is a crucial technique for treating central nervous system and peripheral nervous system disorders. However, the use of invasive electrodes presents risks such as high implantation risk, mechanical stress, electrical connection requirements, power supply difficulties. On the other hand, non-invasive magnetic stimulation has limitations such as centimeter-level focal areas and shallow stimulation depth.
Methods
To overcome these challenges, we propose a minimally invasive approach that involves the injection of a highly conductive, flexible liquid metal (LM) combined with an 8-shaped magnetic stimulation coil (8-coil). This combination aims to enhance the precision and effectiveness of wireless electrical stimulation. An electric field measurement platform was established, and the efficacy of this method was validated through stimulation of the sciatic nerve in mice.
Results
Theoretical analysis and finite element simulations demonstrated that the combination of LM and 8-coil produces a millimeter-scale enhanced vector electric field within tissues. The actual measured electric field distribution closely aligned with theoretical and simulated outcomes. In experiments involving mouse sciatic nerves, 1 μL of LM in a 0.45 T magnetic field significantly increased electromyographic signals and leg movement amplitude by 500%, with no adverse reactions observed.
Conclusions
This method utilizes focused electric fields to improve the precision and effectiveness of neuro-electromagnetic stimulation. It holds promise as a novel approach for precise electrical stimulation.