Measurement of soft tissue deformation at discomfort and pain threshold in different regions of the head.

Understanding of product-soft tissue interface and related discomfort is essential while designing wearable devices. Although pressure thresholds at the perception of discomfort and pain have been measured in the past, associated tissue deformation is yet to be studied. This data can provide a holistic understanding of user discomfort and be a valuable reference for ergonomic product design. Hence, in the current study, tissue deformation at discomfort and pain threshold was measured using an ultrasound indentation device at 18 landmarks for 83 Chinese adults on the head and face. Results show that deformation was higher in the facial region than the scalp and forehead, with maximum deformation in the cheek area and minimum in the forehead region for both thresholds. Also, for most landmarks, the tissue deformation data showed no significant relationship with age and Body Mass Index (BMI). Nearly half of the landmarks exhibited significant gender-based differences. Overall, the measured data showed acceptable within-session and between-session reliability. Practitioner Summary: In this study, tissue deformation was measured in different head regions for discomfort and pain thresholds, and corresponding deformation maps were developed. Measured tissue deformation data showed no significant relationship with BMI and age. This data can be a useful reference in the design, testing, and evaluation of headgears.