Development of a Soft Robotic Arm Compression Sleeve with Tangential Motion for Assisted Lymphedema Management

Abstract

Lymphedema is a chronic condition affecting over one million Canadians, in which impaired lymphatic function reduces the body’s ability to circulate and process lymphatic fluid. Management typically requires ongoing treatment, often including Manual Lymphatic Drainage (MLD) by trained specialists. However, access to these treatments can be limited, while current at-home compression devices primarily apply normal compression rather than reproducing the directional skin deformation characteristic of MLD. Existing active compression garments can also be bulky and non-portable, and may require users to remain relatively stationary during treatment. These limitations motivate the development of alternative wearable technologies that can improve access to treatment while reducing disruption to daily activities. Soft robotics technologies offer a promising approach to addressing these limitations; however, existing wearable soft robotic systems can be constrained by the cost and bulk of pneumatic control hardware, the inability to generate controlled tangential motion along the skin, and limited options for compliant surface-pressure sensing.

One contributor to system cost is the use of high-performance solenoid valves, which can cost tens to hundreds of dollars for precise pneumatic control [1], [2], [3]. In contrast, low-cost miniature on/off solenoid valves under three dollars are widely available and offer an attractive alternative for portable and affordable wearable systems [4]. However, their flow characteristics can vary significantly among valves and operating conditions, and their performance is often insufficiently characterized for direct incorporation into model-based pneumatic control.

To address these challenges, this thesis contributes: (i) an experimental framework for characterizing and modelling the flow characteristics of low-cost solenoid valves, identifying their controllable operating regions, and incorporating the resulting models into closed-loop pneumatic control; (ii) a custom flat, flexible capacitive pressure sensor; (iii) a movable Pneumatic Artificial Muscle (PAM)-based compression cuff and cable-driven locomotion system; and (iv) the integration of these components into an active compression sleeve prototype.

The developed active compression sleeve integrates the mechanical and pneumatic hardware required to apply compression while enabling controlled tangential motion of the cuff along the limb. The primary mechanical, pneumatic, and sensing subsystems were evaluated independently to characterize their performance and demonstrate their feasibility for integration. Full closed-loop operation of the final integrated prototype remains a subject for future work. Nevertheless, the resulting system establishes a foundation for further calibration, control development, and experimental evaluation of a wearable device intended to supplement existing approaches to lymphedema management.