Why intra-epidermal electrical stimulation achieves stimulation of small fibres selectively: A simulation study

Research output: Contribution to journalArticleScientificpeer-review


  • Jun Motogi
  • Yukiya Sugiyama
  • Ilkka Laakso
  • Akimasa Hirata
  • Koji Inui
  • Manabu Tamura
  • Yoshihiro Muragaki

Research units

  • Tokyo Women's Medical University
  • Nagoya Institute of Technology
  • National Institutes of Natural Sciences


The in situ electric field in the peripheral nerve of the skin is investigated to discuss the selective stimulation of nerve fibres. Coaxial planar electrodes with and without intra-epidermal needle tip were considered as electrodes of a stimulator. From electromagnetic analysis, the tip depth of the intra-epidermal electrode should be larger than the thickness of the stratum corneum, the electrical conductivity of which is much lower than the remaining tissue. The effect of different radii of the outer ring electrode on the in situ electric field is marginal. The minimum threshold in situ electric field (rheobase) for free nerve endings is estimated to be 6.3 kV m-1. The possible volume for electrostimulation, which can be obtained from the in situ electric field distribution, becomes deeper and narrower with increasing needle depth, suggesting that possible stimulation sites may be controlled by changing the needle depth. The injection current amplitude should be adjusted when changing the needle depth because the peak field strength also changes. This study shows that intra-epidermal electrical stimulation can achieve stimulation of small fibres selectively, because Aβ-, Aδ-, and C-fibre terminals are located at different depths in the skin.


Original languageEnglish
Pages (from-to)4479-4490
Number of pages12
JournalPhysics in Medicine and Biology
Issue number12
Publication statusPublished - 25 May 2016
MoE publication typeA1 Journal article-refereed

    Research areas

  • characteristics of electrodes, Electrical dosimetry, small fibres, threshold of electrostimulation

ID: 6487159