Hemodynamic sensing of 3D fingertip force using PPG device on proximal part.

This research proposed a novel method to estimate the 3D contact force of a fingertip using a photoplethysmogram (PPG) device on the proximal part of a finger. The proposed method detects non-pulsatile and pulsatile components of PPG signals, extracts eight feature values related to the contact force, and estimates the force by multiple linear regression. In the validation experiments, the participants wore a PPG device at the proximal part of the index finger and applied contact force. Then, the relationship between the contact force and PPG feature values was investigated. As a result, the system was found to be capable of estimating the 3D contact force with a root-mean-square error of 3.5 % of the maximum contact force.