Wearable Lymphedema Massaging Modules: Proof of Concept using Origami-inspired Soft Fabric Pneumatic Actuators

Lymphedema is a non-curative chronic swelling caused by impairment of the lymphatic system, affecting up to 250 million patients worldwide. The patients suffer from low quality of life because of discomfort and reduced range of motion due to the swelling. Severe swellings can be immediately mediated with special massaging technique known as the Manual Lymphatic Drainage (MLD). Limitations of MLD involves long travel distances, the cost of regular treatment sessions, and the lack of lymphedema specialists. Since MLD is performed very gently, described as caressing a baby's head, soft wearable robotics with its inherent compliance and safety is the perfect solution to creating a light and safe wearable lymphedema massaging device. In this paper, origami-inspired soft fabric pneumatic actuator is developed that creates not only normal force, but also shear force which is essential in the performance of MLD. The shear is created by the unfolding of the Z-shaped fold-lines as the actuator is inflated. One Z-folded actuator module of 30 x 60 mm dimension with a single fold of 15 mm fold height creates maximum shear force of about 1.5 N and stroke displacement of about 30 mm when subjected to compression loading of 5 N. The range of forces exerted can be tuned by varying the tension of the compressive clothing covering the actuators, and the stroke displacement can be varied by changing the parameter of the actuator module itself, such as the fold height and the number of the folds. The modules can also be repeatedly actuated under compressive clothing, and therefore, the developed actuator modules have high potential as a wearable massaging device.