Advancing Medical Training with Mixed Reality and Haptic Feedback Simulator for Acupuncture Needling

Traditional acupuncture training often lacks consistent, objective feedback, while current extended reality (XR) solutions rarely include quantitative assessment. This study developed and evaluated a feedback-enabled mixed reality (MR) acupuncture simulator to improve skill acquisition through depth-responsive guidance. The system, used on Microsoft HoloLens 2, combines a MetaHuman-based virtual patient with expert-designed acupoint geometries. It provides depth-dependent vibrotactile cues via a wearable haptic device and calculates a composite score from normalized metrics, including insertion depth, angular deviation, tip-to-center distance, and task duration. Ten participants (eight novices and two experts) performed needle tasks at LI4, LI11, and TE3 across two sessions. Mean depth error decreased from 6.41 mm to 3.58 mm, and task time from 9.29 s to 6.83 s. At LI11, beginners improved in achieved depth (16.24 ± 1.88 mm to 19.74 ± 1.23 mm), reduced angular deviation (27.83° to 15.34°), and shortened completion time (38.77 s to 13.28 s). Experts outperformed novices (69.25 ± 21.64 vs. 56.26 ± 23.37), confirming construct validity. Usability evaluation showed a mean overall score of 4.46 ± 0.51 and excellent reliability (McDonald's ω = 0.93). These results demonstrate that expert-informed scoring and depth-responsive haptic feedback substantially enhance accuracy, efficiency, and learning confidence, validating the system's technical robustness and educational readiness for clinical acupuncture training.