Soft Exoskeleton Mimics Human Cough for Assisting the Expectoration Capability of SCI Patients

This paper describes the design of a bionic soft exoskeleton and demonstrates its feasibility for assisting the expectoration function rehabilitation of patients with spinal cord injury (SCI). Methods: A human-robot coupling respiratory mechanic model is established to mimic human cough, and a synergic inspire-expire assistance strategy is proposed to maximize the peak expiratory flow (PEF), the key metric for promoting cough intensity. The negative pressure module of the exoskeleton is a soft iron lung using layer-jamming actuation. It assists inspiration by increasing insufflation to mimic diaphragm and intercostal muscle contraction. The positive pressure module exploits soft origami actuators for assistive expiration; it pressures human abdomen and bionically pushes the diaphragm upward. Results: The maximum increase in PEF ratios for mannequins, healthy participants, and patients with SCI with robotic assistance were 57.67%, 278.10%, and 124.47%, respectively. The soft exoskeleton assisted one tetraplegic SCI patient to cough up phlegm successfully. Conclusion: The experimental results suggest that the proposed soft exoskeleton is promising for assisting the expectoration ability of SCI patients in everyday life scenarios. Significance: The proposed soft exoskeleton is promising for advancing the application field of rehabilitation exoskeletons from motor functions to respiratory functions.

Automated summary

This study describes the design of a bionic soft exoskeleton to assist in expectoration function rehabilitation of patients with SCI. Experimental results show significant improvement in PEF cough index with respiratory assistance across different test subjects, indicating great potential in helping SCI patients with phlegm expulsion in daily life.