Source: Zhongguancun Online
Researchers in Brazil published a research report aimed at improving the characteristics and accessibility of robotic mechanical prostheses through 3D printing technology. Mechanized prostheses may provide a viable and low-cost alternative for simulating the functioning of people with disabilities. However, its high value means that the purchasing power of these devices is low, making them unavailable.
In their thesis, the researchers detailed the use of 3D printing technology to improve the upper limb mechanical prosthesis, the anthropomorphic features achieved through programming, and importantly, they also highlighted the low financial cost of the device.
Using 3D printing technology to improve the availability of medical equipment
The research report first details the current status of the prosthetic market. Although the development of such prosthetic devices for the rehabilitation of amputees has been evolving, researchers explain that mechanical prostheses have a commercial disadvantage. “The price of this type of prosthesis is higher than the purchase conditions of a large part of the people who are undergoing rehabilitation treatment. People with low purchase value will ultimately not be able to purchase prosthetics, so they will choose mechanical control and low interaction with users. Non-automated mechanism. “
In view of this problem, the research then positioned 3D printing as a potential technology for designing effective prosthetics and positioning it as a low-cost effective prosthesis technology: “A model with similar characteristics to humans can be printed so that it has close to the real human Resource of parts. “
In fact, 3D printing has been used to help increase the availability of customized medical devices such as the prostheses of amputees around the world. Recently in the 3D printing industry, we detailed how the Dutch non-profit organization 3D Sierra Leone provided customized 3D printed prosthetics for patients in this West African country. Using 3D printing technology, 3D Sierra Leone is committed to improving the lives of patients in Sierra Leone who have undergone amputation but are unable to access related medical services.
In Syria, 3D printing technology has also been used to provide prosthetics, because in the ongoing civil war, traditionally manufactured prosthetic equipment has been difficult to find. The British charity “Syria Relief” (Syria Relief), which works in Syria, has begged the British Department for International Development (DFID) to provide 3D prosthetic funds for children in the country.
3D printed mechanical prosthesis
In their work, the researchers introduced the development and improvement of upper-limb prosthetics with anthropomorphic features and low economic costs. The researchers used 3D printed parts together with electromyography (EMG) sensors and strain gauge force sensors.
The design of the prosthesis was modeled in AutoDesk CAD software and then 3D printed using the AnetA8 3D printer. Since AnetA8 is a low-cost system, it is not equipped with a depth sensor to detect the depth sensor of the extruder nozzle approaching the table, which may cause a collision. Therefore, the researchers chose to modify the system, implement inductive sensors to detect metal materials, and update the firmware and calibration.
Each component on the prosthesis is designed to interact mechanically, which is equivalent to the bone structure present in the composition of the human hand, consisting of 27 bones. “Therefore, at the end of the structural modeling, it is equivalent to 37 pieces. All the structures are completed by the internal cables to complete the movement of the fingers.”
The internal structure of the prosthesis includes perforations with a diameter of 2 mm to allow the cable to pass through the device. The fist is fixed on the hand and fingers with steel screws, and the finger links are connected with hard copper.
The researchers chose PLA as the first stage 3D printing material. Because its melting point was 190 ° C, the researchers chose PLA as the 3D printing material. The parameters of the 3D printing process were established using Simplify3D V4.1 software to determine the amount of filament required and the length of the printing process. In order to realize the movement of the prosthetic fingers, a servo motor with a large torque of 13 kg / cm is used when the power is 4.8V, and the working voltage is 4.8-7.2V. The metal gear makes the finger wear less and the torque is more reliable. In order to measure the pressure of the finger on the surface of the palm, a force sensor with a measuring range of about 100 grams to 10 kg is used, and the detection area is a circle of 15 mm and the detection range is 15 mm.
When testing the capabilities of the device, the researchers explained. “Facts have proved that, given the measurement results between the prosthesis and the target muscle, the measurement results between the prosthesis and the target muscle are measured and converted into the movement of the device, so the sensing application is satisfactory. Therefore, the force sensor can stop the movement and prevent damage to the joint structure of the prosthesis when the finger is closed. “
The final acquisition value of the project is R $ 2,000 (US $ 374), while the current average price of mechanical prostheses on the market is about R $ 200,000 (US $ 37,408).
At the end of the paper, the researchers detailed how 3D printed mechanical prosthesis research advances the research of affordable mechanical prosthetics. “For future research involving mechanical prosthesis improvement projects, it may provide sensors that can simulate touch on the surface of human skin, as well as insert new force sensors and electromyography sensors to better deal with stimuli that dissipate in the muscle compartment signal.”