While technology designed to replace bones has long been used in humans in the form of prosthetics and implants, muscles have proved to be more difficult to replace because of their elastic nature.
But now a Japanese research team has designed a wearable robot designed to support a person's hip joint while walking.
"With a rapidly ageing society, an increasing number of elderly people require care after suffering from stroke and other-age related disabilities. Various technologies, devices, and robots are emerging to aid caretakers," wrote Shinshu University professor Minoru Hashimoto, noting that several technologies meant to assist a person with walking are often cumbersome to the user.
"[In our] current study, [we] sought to develop a lightweight, soft, wearable assist wear for supporting activities of daily life for older people with weakened muscles and those with mobility issues."
The wearable system consists of plasticised polyvinyl chloride (PVC) gel, mesh electrodes, and applied voltage. The mesh electrodes sandwich the gel, and when voltage is applied, the gel flexes and contracts, like a muscle.
"We thought that the electrical mechanical properties of the PVC gel could be used for robotic artificial muscles, so we started researching the PVC gel," said Hashimoto. "The ability to add voltage to PVC gel is especially attractive for high-speed movement, and the gel moves with high speed with just a few hundred volts."
In a preliminary evaluation, a stroke patient with some paralysis on one side of his body walked with and without the wearable system.
"We found that the assist wear enabled natural movement, increasing step length and decreasing muscular activity during straight-line walking," wrote Hashimoto. The researchers also found that adjusting the charge could change the level of assistance the actuator provides.
Prototype PVC gel mesh
Next, the researchers plan to create a string actuator using the PVC gel, which could potentially lead to the development of fabric capable of providing more manageable external muscular support with ease.
In 2016 scientists developed a patch that senses the electrical activity of muscles, which could represent a breakthrough in emotion reading and therapy for strokes patients.
