A novel photocurable insulator material for autonomic nerve activity recording

The two-component, addition-curing silicone glue is widely used as an insulator for autonomic nerve activity recording. Due to its high fluidity before curing, a sizable mass of the glue is needed to completely cover the electrode tips, which may cause mechanical stress on the nerve. To overcome this problem, we designed a novel photocurable insulator material composed of Vaseline and 1,12-dodecanediol diacrylate (50:50 wt%) together with a photoinitiator, camphorquinone, at 0.25 wt%. This material had an appropriate viscosity of 0.18 Pa s at 25°C and was converted to a soft solid upon an arbitrary timing of photoirradiation. The compressive force per mm deformation of the resulting solid was 155.5 kPa at 1 min of photoirradiation. The impedance of the solid for 1 mm length and 10 mm2 cross-sectional area was above 1 MΩ. In anesthetized rabbits, a very small mass of the photocurable material was able to cover the electrode tips and the nerve in situ. Changes in both the aortic depressor nerve activity and renal sympathetic nerve activity were stably recorded. These results indicate that the photocurable material developed is useful as an in vivo insulator material for autonomic nerve activity recording.