Jul 4, 2022

Noninvasive Stimulation of Peripheral Nerves using Temporally-Interfering Electrical Fields

Boris Botzanowski, Mary J. Donahue, Malin Silverå Ejneby, Alessandro L. Gallina, Ibrahima Ngom, Florian Missey, Emma Acerbo, Donghak Byun, Romain Carron, Antonino M. Cassarà, Esra Neufeld, Viktor Jirsa, Peder S. Olofsson, Eric Daniel Głowacki, and Adam Williamson, Advanced Healthcare Materials 2022, Volume 11, Issue 7, Article No. 2200075, online 24 June 2022; doi: 10.1002/adhm.202200075

Electrical stimulation of peripheral nerves is a cornerstone of bioelectronic medicine, and the possibility to accomplish peripheral nerve stimulation (PNS) noninvasively without surgical implantion of devices may open the way to important new medical applications. In this work, we demonstrate that relatively high-frequency (3 kHz) sine-wave carrier currents injected by two pairs of cutaneous electrodes with a frequency offset of 0.5–4 Hz can temporally interfere at deep peripheral nerve targets to effectively induce effective nerve stimulation at the offset frequency. The murine sciatic nerve model and in silico models of temporal interference nerve stimulation (TINS) were used to execute in vivo experiments designed to investigate exposure metrics relevant to TI at the nerve level for various electrode configurations. It was found that effective stimulation is achieved at current amplitudes significantly lower than those required for standard transcutaneous electrical stimulation. We also demonstrated that the use of flexible and conformable on-skin multielectrode arrays can facilitate precise alignment of TINS onto a nerve. TINS opens the possibility to perform precise noninvasive stimulation with depth and efficiency that has previously been impossible with transcutaneous techniques.

The scientific and technical impact of the study can be summarized as:

  • TINS effectively stimulates peripheral nerves at currents smaller than those required by conventional noninvasive stimulation approaches
  • The use of conformal multi-electrode arrays permits optimization of TINS by positioning the electrode to align the electric fields with the target nerve
  • The IT'IS tissue properties database and predefined tissue assignment tags in the NEUROFAUNA model were used to assign the dielectric properties of the target nerve 
  • Further studies are needed to explore additional applications of TINS for research and for clinical applications