Assistive technology is a term for assistive, adaptive, and rehabilitative devices for people with disabilities and the elderly. 3D printing(3DP), also known as additive manufacturing, is a rapid prototyping technology whose basic principle is to use powdered metal or plastic and other bondable materials to construct objects in a layer-by-layer manner. Usually, digital design is used to build a three-dimensional model, and then materials are virtual to reality. It has shown great advantages in precise assistance to the disabled and has formed a one-stop assistance strategy in rehabilitation treatment, unimpeded life, and sunny employment. An integrated, scientific, and thorough model of helping the disabled is novel, scientific, and feasible, and has a strong empowering effect on the disabled. Therefore, 3D printing has great research significance and application value in the development of the disabled. According to the characteristics of 3D printing technology, it can be divided into the following mainstream processes. Fused deposition (FDM), also known as fused filament deposition, mainly uses thermoplastic materials such as ABS resin, polylactic acid (PLA), and nylon as printing materials, and processes the materials with high-temperature nozzles. , stacked layer by layer until the three-dimensional product is formed. It is characterized by a wide range of materials, low cost, and high speed, and can be used for small batch production.
Selective laser sintering (SLS), using powders of metal, ceramics, plastics, and other materials as raw materials, uses lasers to selectively sinter solid powders in layers and makes the sintered solidified layers stacked layer by layer to form products of the desired shape. It is characterized by various materials, high utilization rates, and high precision. Stereolithography (SLA) uses liquid photosensitive resin as material, and under computer control, an ultraviolet laser makes it solidify and form. It is characterized by high molding precision and large molding size and can produce more complex hollow parts. Digital Light Processing (DLP), using photo-hardening resin as the material, uses a digital light source to project layer by layer on the surface of liquid photosensitive resin, and then solidify and shape layer by layer. It is characterized by ultra-high precision, a smooth surface, and good material. There are other emerging processes, such as metal powder laser selective melting (SLM), selective heat sintering (SHS), electron beam free forming manufacturing (EBF), electron melting molding (EBM), and so on.
3D printing assists in the precise rehabilitation of the disabled.
Rehabilitation service is an important part of modern health services. Precise rehabilitation refers to providing patients with personalized and comfortable rehabilitation programs through 3D printing so that the disabled can enjoy more intimate and thoughtful treatment services.
1. 3D printing helps the physically disabled
3D-printed prosthetics are artificial limbs assembled to compensate for the limb defects of amputees. Traditional prosthetics are simple in shape, bulky, do not meet the requirements of biomechanics, have poor practicability, and are expensive, so they cannot meet the needs of personalized and precise treatment for disabled people. Using 3D printing technology to make prosthetics, 3D scanning creates a three-dimensional model that meets the size of the patient's limbs. It is light in weight, short in molding time, and can fully meet the physiological needs of disabled people. The shell of the prosthesis can also be customized. According to the limb data of the disabled, the information is processed and matched in the computer, and the shell style of the 3D prosthesis can be printed according to the individual needs of the patient, which has a high degree of personalization and stronger practicability. The 3D printed prosthetic device "NexStep" developed by German 3D printed prosthetics manufacturer Mecuris has passed the European Union's CE certification. The company uses 3D printers to print upper limb prostheses for children and adults in need for free or at low cost and has provided prosthetics to more than 10,000 recipients so far.
Picture 1 prosthetics
2. 3D printed orthotics. The purpose of orthopedic surgery is to support or restore human mobility according to individual needs. Orthotics are applied to the limbs, trunk, and other parts to treat bone, joint, muscle, and nerve disorders and compensate for their functions through fixation, support, and correction. Because the design of orthotics must match the patient's anatomical structure and treatment needs, currently orthotics need to be produced according to customized structures or in small batches. The digitally produced orthosis by 3D printing has higher design flexibility, and its functionality, comfort, and safety are more in line with the individual needs of patients. A postgraduate student in bioengineering in Poland has designed a lightweight custom finger orthosis for a patient with quadriplegia to help the patient's fingers easily grasp objects. A 3D printed scoliosis corrector developed by UNYQ, a manufacturer of personalized prosthetics and orthotics, is made of nylon, with an average weight of 300-600g and a thickness of only 3.5mm. It is breathable, light, and fits well. After the patient wears this orthosis, it can be easily hidden in clothes, satisfying the therapeutic effect without affecting the appearance.
3.3D printing helps the hearing disabled
Among the tools for treating hearing disabilities, mild patients mainly use hearing aids, and most patients with severe hearing impairment use cochlear implants. Traditional custom-made hearing aid shells are generally made by hand, which takes a long time to make, high cost, certain errors, and poor wearing comfort. 3D printing technology uses a 3D scanner and computer software to extract the contour model of the human ear for design and processing and uses a 3D printer to manufacture the hearing aid shell. This method is faster, more convenient, more efficient, and labor-saving than the traditional method, and the manufactured hearing aid shell fits the human ear higher, more comfortable to wear. Hearing aids are compensation for hearing, while cochlear implants are the basic treatment for patients to return to the world of sound through surgery. Cochlear implants are currently the most effective implantable solution for reconstructing hearing in patients with severe or extremely severe sensorineural hearing loss. Although cochlear implants have been used clinically for decades, they cannot accurately evaluate the voltage/electric field distribution caused by cochlear implants in the real environment of the human body, so the current cochlear implants cannot help patients fully recover or rebuild hearing. The research team used the "3D printing + machine learning" model to print the bionic cochlear model, which can highly imitate the patient's voltage distribution and explain the occasional atypical voltage distribution in the patient's ear. The "3D printing + machine learning" model provides a model with strong operability, low cost, and no medical ethics issues to help the development of a new generation of personalized cochlear implants.
Picture 2 hearing aids
