The Million Hands team.

Million Hands: A prosthetic finger for everyone

Team update, Global Product Development | By team Million Hands: Alejandro García Salas, Daniel Lim, Holly Stein, and Jeff Ying

Over 541,000 people in the United States have gone through an upper limb amputation. These amputations, which are caused by vascular disease, infectious disease, and traumatic injury, are expected to double in number by 2050.

There are myriad prosthetic hands on the market, most of which provide a full prosthetic hand for patients with above-wrist amputation. However, design for partial finger amputees, who constitute 61% of the upper-limb amputee population, is lacking in both academia and medicine.

Million Hands’ motto is to provide a functional prosthetic finger that can boost the confidence of people with partial fingers. The team spun out of Sophie’s Super Hand, a project from 2015 in which one of our team members, Daniel Lim, had noted the unmet needs in available prosthetic hand designs. Specifically, the design for partial hands was unexplored, despite the tremendous need among users. To learn more about Sophie’s Hand, check out this video.

After we had developed a functional prototype, the Global Product Development (GPD) class offered by the Jacobs Institute stood out as a way to move forward on bring this invention to market. The core concept of the product and services we have developed through GPD stems from adjusting the whole design by changing a few parameters: namely, the girth and length of the finger. The whole assembly is then fabricated using digital fabrication tools such as 3D printing and CNC milling.

The GPD course has transformed our thinking: we have moved from thinking narrowly about a product toward more user-oriented and process-focused development. Based on these insights, we have made two major changes to our process.

First, we are now concentrating on reducing the lead time to get a prosthetic hand down to one month, whereas other prosthetic finger options in the market generally take six months to a year for the fitting process and involve long lead times without much communication. Our research indicated that these long delays comprised the main pain point amongst users.

Second, we targeted minimizing the number of design decisions that would be required for the designers and fabricators, in order to reduce stress during the design stage. Currently, in the process of fabricating a prosthetic finger, prosthetists have to fit and adjust the design from the manufacturer multiple times to optimize the assembly. By reducing the design parameters that need to be considered, we expect that the whole process could be simplified to obtain a functional prosthetic finger.

For our next steps, we are planning on refining the business plan and the final prototype to be prepared for user testing of the whole structure of the service. After the testing, plans for fabrication of the components will be set, based in part on our upcoming class visit to Hong Kong and Shenzhen.

Follow along with the Million Hands team and their Global Product Development classmates as they continue to develop their projects, drawing from expert insights, a field trip to Hong Kong and China, and more along the way.Over the course of the semester, we’ll be sharing blog posts from each student team here on Medium (read a post from Team JARAD here). In the meantime, learn more about the course here.


[1] Ziegler-Graham, K., MacKenzie, E. J., Ephraim, P. L.,Travison, T. G., and Brookmeyer, R., 2008. “Estimating the prevalence of limb loss in the united states: 2005 to 2050”. Archives of physical medicine and rehabilitation, 89 (3), pp. 422–429.