Stretchable triboelectric sensor for measurement of the forearm muscles movements and fingers motion for Parkinson's disease assessment and assisting technologies

Abstract

Parkinson's disease (PD) is a degenerative, neurological disease that causes motor dysfunctions on the patient. Currently, the symptoms and progression of the disease are assessed by physicians who diagnose through careful observation, according to the Movement Disorder Society (MDS)-sponsored Revision of the Unified Parkinson's Disease Rating Scale (UPDRS). In this manuscript, we report a portable sensor device based on a flexible Triboelectric Nanogenerator (TENG) formed from a dielectric material with a size of 4 cm × 3.5 cm and an aluminium (Al) electrode with dimensions of 2 mm × 3 mm, to monitor the movement of forearm muscles and tendons. When the hand or fingers extend or flex, the short gap between the dielectric polymer and the small conductor changes, generating a voltage due to triboelectric contact. The device is used to assess localized bradykinesia and rigidity of fingers and hands, as well as wrist and arm tremors. The voltage signal of the proposed sensor shows different waveform shapes, time duration and amplitude for each level of classification from ‘normal’ to ‘moderate’ status, described on the MDS-UPDRS examination of hand movement, finger tapping and pronation–supination movement. Hence, we demonstrated that the proposed sensor can potentially be used for quantification of the symptoms and diagnosing. In addition, single finger motion tracking is also achieved by placing the triboelectric sensor in different positions around the forearm, close to the tendon connected to the finger under test. This way we avoid the placement of the sensor directly on the fingers, improving comfortability and long-term wearability. The presented TENG sensor is fully integrated with the processing and the transmission board exploring new opportunities for triboelectric transducers in small motion detection of muscles. The future aim of this research is to provide real-time monitoring of the disease progression as feedback for personalized treatment of the PD patients.