Design, Development and Validation of a Novel Mechanical Pain Inducer and the EMG Signal Analysis for the Induced Mechanical Pain

The measurement of physiological parameters is a crucial method for measuring pain objectively. Precise measurement of physiological parameters, including electromyography (EMG), can categorize the pain intensity levels objectively. This work designed and developed a novel mechanical pain inducer to induce pain in human subjects and analysed the EMG signal for normal (pain-free or no pain) and different intensity of pain levels (i.e., threshold, moderate, and tolerance). This mechanical pain inducer applies force to a healthy individual’s hand to create different pressure intensity levels to cause pain. Twenty volunteers (male 11, female 9) in the age range of 20–40 years participated in this experiment. The different levels of pain intensity are measured using the numerical pain rating scale based on the participant's reaction. The EMG signal was acquired for both the normal state and the different pain levels. The calculation for the root mean square (RMS) value and analysis of variance were carried out on the EMG signals for normal and each level of pain. The investigation of the RMS value of the EMG signal shows that as the intensity level of pain increases, the RMS value of the EMG signal also increases accordingly for each level of pain. This indicates that the induced pain can affect the electrical potential of the EMG signal. Also, a significant mean difference in the RMS value is observed between normal and different intensities of pain levels at p < 0.05.