100 million people around the world need orthopedic devices. However, according to the World Health Organization (WHO), only 5% to 15% of people who need assistive technology and assistive technology can access them. Production is low, and quality is often limited. The techniques used are often and by necessity simple, dictated by the degraded environment of most of NGOs’ fields of action.
In particular, it is to respond to this problem that the Innovation for Humanity research and teaching chair has just been created. It brings together the INSA Alliance and Handicap International. The objective is to bring out technical and scientific responses to the very concrete problems encountered in the field.
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The promises of 3D printing for the manufacture of prostheses
The manufacture of prostheses used in the humanitarian field has evolved well: they were first made of woven bamboo by users and technicians with wood, or even (and it is an irony of the situation) made from shell packaging by users. Today, the devices are often made of thermoformed polymers and made from a plaster mold sculpted as close as possible to the anatomy of the missing limb… Prostheses are becoming increasingly light, functional, and therefore accepted.
Since 2016, Handicap International has carried out several projects on the potential of telerehabilitation and additive manufacturing technologies in various contexts (humanitarian, development, refugee camps) to develop and strengthen rehabilitation services and improve access, the quality, and cost of services. Thanks to the scanner, 3D printing, and videoconferencing, we can re-educate patients without a specific workshop on site. While 3D printing does not completely replace traditional fitting methods, it will allow more people to access functional rehabilitation, for example, in areas where rehabilitation centers are too far away and in areas of conflict. 3D printing has shown promise in the first countries where it was deployed on an experimental basis.
Scientific challenges and necessary acculturation
While 3D prostheses represent real hope and a credible alternative to conventional prostheses, adapting to local situations and allowing populations to take ownership is a real challenge. The stump of the amputee is now scanned on-site using small medical scanners.
The measurements are then transferred to centers of expertise to create a 3D model of the prosthesis, which is then used to produce it on-site, on small transportable machines, and imported commercial polymer filaments. The cost of these prostheses produced by additive manufacturing is still too high (between 3 and 5 times more expensive than a conventional prosthesis). They also raise the question of dependence on raw materials, that of the durability of materials, and the training of personnel to use these digital technologies.
The challenges of 3D printing prostheses are therefore numerous:
- In the field of materials science, polymers, which could be of local origin, are reinforced with vegetable fibers to make them more resistant and durable. The recycling of waste generated by the manufacture of prostheses and orthotics is a real subject. 3D printing would limit waste production or even allow the reuse of certain plastic waste, which is legion in some countries. Why not use waste thermoplastic polymers to manufacture yarns or granules for printing on-site? Why not try making printable yarns from bio-based polymers?
- In the area of design, then. 3D printing makes it possible to create shapes and architectures that conventional technologies do not allow. It is a shame to note today that 3D prostheses are heavier than conventional prostheses simply because their shape is identical and the materials used are often too fragile. It is necessary to work on the quality of the polymers used and optimize the shapes. 3D printing makes it possible to remove material from places that are not mechanically stressed and, therefore, to reduce mass and cost without compromising functionality. This is one of the objectives that will be pursued in the INSA laboratories’ work on the subject, to gain in mass and reduce costs.
- Finally, in the field of imaging and digital sciences. We could imagine taking the physiological measurements on the spot, directly with a cell phone camera instead of a scanner. A few images taken at different angles and efficient 3D reconstruction algorithms could then do the trick. It remains to be able to create the model directly on site from these images.
Jean ‑ Baptiste Richardier, the co-founder of Handicap International, spoke of the importance of “not giving in to the fever or intoxication of innovation, of always being in the field of reasonable innovation, in the field of the possible.” Establishing the “field of the possible” requires time, research and experimentation, restraint, and even giving up to achieve a “crossbreeding” of good quality, a source of progress.
Digital sciences, which include 3D printing, are revolutionizing the engineering profession: decision support, analysis of massive amounts of data, speed of calculations and exchanges, personalized manufacturing, connected prostheses, etc.
Appropriation of these new technologies is essential and must be integrated into research. Digital technology creates hopes, but also anxieties, even fractures. One of the pitfalls would be to impose our technological knowledge and our solutions in contexts where they are not applicable. We must therefore educate and train ourselves, train our students to understand and integrate degraded environments. There is an ethical issue in keeping the technological dimension in its rightful place, by analyzing what we save, but also what we lose. 3D printing is already giving a helping hand to people who make their own way and who appropriate the technology by making prostheses at home or in fab labs. In countries where HI operates,
It is essential to involve students in doctoral studies or engineering study projects, on the one hand. They are very demanding of these meaningful subjects and, on the other hand, because they also have great ideas that deserve to be developed.
In addition to purely technical questions, we, holders of the Innovation for Humanity chair and our colleagues, will then have to ask ourselves the questions that remain fundamental:
- How to establish the field of possibilities on-site, in terms of logistics, networks, intervention environment, and capacity of appropriation by the local populations?
- How to mobilize researchers, engineering students, companies to provide scientific keys to humanitarian challenges and integrate humanitarian issues into our training?
Going further: towards smarter mine detection drones
One of the major challenges of Handicap International’s interventions is to provide longer-term security in areas that have experienced conflict, particularly through humanitarian demining, to restore healthy land to populations as quickly as possible. The use of drones already makes it possible to map risk areas. We have started work whose objective is to equip them with sensors and analyze the data collected using artificial intelligence and machine learning techniques to detect signs of mines, such as the presence of carcasses. Animals, cars, or explosion signs. The use of other types of sensors such as infrared sensors is a promising avenue for detecting buried mines in certain environments.
Another issue is the anticipation of the dynamics of humanitarian crises through excavation, automatic analysis, and data visualization from a wide variety of sources (social networks, socio-economic data, city maps, or road networks). One can think of the modeling of crowd movements that can occur during disasters or modeling the current pandemic. The classic epidemiological models have limits to predict the spread of disease. Another major area of application will concern the management of the means to be deployed in the field, particularly the optimization of the logistics of delivering emergency equipment in the last mile.