Haptic simulation for acupuncture needle manipulation

Background: Stimulation degree, biomechanical force, and de qi sensation are the three major components of needle manipulation. To date, it has been difficult to measure all three components quantitatively. Objectives: To (1) measure and compare biomechanical forces of six human acupoints in vivo during haptic manipulation, (2) develop phantom acupoints with biomechanical forces similar to those of human acupoints, and (3) validate the newly developed phantom acupoints based on assessment by doctors of Korean medicine. Methods: The biomechanical force and needle grasp sensation (i.e., the practitioner's de qi sensation) of six human acupoints (LI4, LI11, LR3, ST36, ST25, and BL25) were assessed in 16 participants upon stimulation with the twisting manipulation technique. On the basis of biomechanical data from these human acupoints, phantom acupoints that generated similar biomechanical forces were developed by using 1%-7% agarose gel. Results: In humans, the mean torque amplitudes of the six acupoints differed significantly. In the phantom, the biomechanical force was dose-dependently greater in higher-concentration agarose gel phantom acupoints. Biomechanical force and the needle grasp sensation were significantly correlated in both human and phantom acupoints. Importantly, practitioners could not discriminate between human and phantom acupoints, suggesting that the validity and credibility of the phantom acupoints are sufficient for applications in education and research. Conclusions: Application of force-validated phantom acupoints based on human data will be a helpful tool for training and will contribute to a more comprehensive understanding of the characteristics of acupuncture manipulation.