A bio-inspired deformable mouthpart device with adaptive control for negative pressure therapy on unstructured limb surfaces

Negative pressure (NP) therapy is effective in managing chronic lymphedema of the extremities. However, the seal formation of the general head (GH) can fail due to the interspace between the lip and the irregular skin surface on limbs before suction, resulting in the inefficiency of therapy, prolonging the time required for physiotherapy, and increasing the workload of physiotherapists. In this letter, we present a bio-inspired head (BIH) that uses adaptive control for NP therapy on unstructured surfaces. Its lip is designed with soft material inspired by the bloodworm to ensure safe human contact. Additionally, the lip size can be changed with the variation of the cavity pressure, and sensors on the lip could provide contact feedback. An adaptive control method is proposed for autonomous suction on unstructured surfaces. Several experiments were carried out to illustrate the characteristics of this novel head with a deformable lip and contact detection, while the adaptive control method for the NP suction on the unstructured surfaces was validated by phantom and body experiments. Compared with the GH, the results showed that the BIH with adaptive control could automatically fit the irregular arm structures to form a seal and complete the NP suction with a higher success rate(SR).