In recent years, Soft Robotics technology has developed rapidly. Unlike traditional robots, software robots have the advantages of high flexibility, safe operation, light weight, simple production, and low manufacturing cost. Their applications are currently mainly in various industrial grippers and medical / rehabilitation devices. The core component of the software robot is composed of flexible materials. How to choose the appropriate materials and manufacturing methods so that it can not only meet the design requirements, but also bear the proper functions. This article introduces the software rehabilitation mechanical gloves invented by Professor Tang Qiyu of the Chinese University of Hong Kong and his team. The software driver unit made of ACEO® 3D printed silicone provides us with a new idea and solution.
The latest development of software rehabilitation manipulator
Stroke is one of the main causes of disability. One person has a stroke every 6 seconds in the world, half of them in China. Hand paralysis is one of the common and difficult sequelae of stroke. The first 3 months after the stroke is the golden period of recovery of hand function may return to the best state. Studies have shown that through the same and repeated movements of damaged hands, the brain can gradually sense and restore motor control functions, thereby promoting recovery after stroke. Currently, several hand rehabilitation devices have been developed to replace expensive and time-consuming physiotherapists. However, the existing devices are heavy and bulky, and most of them cannot provide assistance to patients in daily life, such as holding simple objects, which is also a problem caused by the spasm of the hand after stroke.
Recently, a silicone 3D printing software rehabilitation mechanical glove invented by Professor Tang Qiyu, Professor Li Zheng of the Chinese University of Hong Kong and their team has solved these problems well. This lightweight, soft mechanical glove can be tailored to the size of the patient ’s fingers and palm. It uses WACKER ’s ACEO® silicone 3D printing technology and uses a soft rubber driver to assist patients to control their hand muscles to flex and stretch their fingers. , To help improve the patient's hand mobility in daily life, and also provide patients with a personalized and affordable rehabilitation training program. At the 47th Geneva International Invention Exhibition held in April 2019, this soft mechanical glove won a silver medal.
ACEO® silicone 3D printing
The reason why 3D printing is used to make the soft rubber drive for mechanical gloves is because the traditional mold-making process requires many steps and long time. 3D printing can reduce the steps of making soft rubber drivers, greatly shortening the production cycle. In addition, 3D printing also provides design freedom. ACEO®'s unique drop-on-demand inkjet technology enables unprecedented product design and complex geometric structures (such as hollowing, cornices, etc.) to be realized, while retaining the excellent properties of silicones, such as high elasticity, heat resistance, UV resistance, Stretching and compression deformation etc. These properties can be preserved throughout the ACEO® printing process, so WACKER ’s 3D printed products are comparable to those produced by processes such as injection molding or rapid compression molding.
According to the main member of the invention team, Honghao Lin, PhD student of the Chinese University of Hong Kong, the materials required for the software driver designed by him focus on the elongation and durability that the material can provide in the case of large deformation. Before enabling ACEO® 3D printing silicone, the team also tried similar rubber materials provided by two other 3D printing manufacturers, but the durability of these products was very low and could not support large deformation. "We need silicones that can withstand high-strength pressure and large deformations for a long time. We found that ACEO® 3D printed silicones can meet these requirements," Xiang Haolin explained.
Soft drive and its development prospects
The soft rubber actuator contains a silicone elastic airbag, and an inextensible bead at the bottom of the component, which acts as a torque compensation. When the airbag is subjected to fluid (liquid or gas) pressure, the airbag will roll up toward the side of the bead, and the driver will cause the finger to bend. After the fluid pressure is reduced, the balloon extends the fingers wearing the device to assist the patient to complete a complete opening and closing hand movement.
A few days ago, after putting on this soft rehabilitation mechanical glove equipped with a soft rubber drive, a stroke patient could smoothly open and close the palm of his hand, and successfully grabbed a Chinese chess piece and screwed it with another normal hand. towel.
"We are also improving the durability and elongation of the material during bending movement. If the material strength is sufficient, we can apply more pressure to the soft rubber actuator, thereby further enhancing its output strength." Xiang Haolin said "We also hope to be able to 3D print a larger number of soft rubber drives at one time. Of course, even in commercial mass production, quality is still the first factor."