By Saemmool Lee
“Million Hands,” a 2017 CITRIS seed-funded project that aims to build an open-source platform for customizable, functional, and low-cost prosthetic hands, has been making progress in developing 3D-printed prosthetic hands with more robust capability.
According to Alice Agogino, a Berkeley mechanical engineering professor and one of three principal investigators of Million Hands, the project was motivated by “Sophie’s Super Hand,” a custom-fitted, 3D-printed prosthetic hand designed for Sophie Mercer by graduate student Daniel Lim in 2015. Sophie’s Super Hand provided the aesthetics of a “Super Hand” along with some functionality – the ability to pick up small items such as toys and foods, for example. The Million Hands project team has been developing hands capable of grabbing and holding objects, and building models that can easily scale based on users’ needs as they grow.
“During the past year, students have been able to design and prototype a functional 3D-printed prosthetic hand,” says Grace O’Connell, Berkeley mechanical engineering professor and co-investigator. “We can have a prosthetic hand that opens and closes using readings from the user’s own muscles. Now, we need a way to semi-automatically scale our design for kids of all sizes based on users’ palm and limb size.” The readings are taken via myoelectric sensors, which detect the electric activity in muscles. They are placed on the skin over various muscle groups.
Lim, who graduated from Berkeley with a master’s degree in 2015, had worked on the project in the CITRIS Invention Lab with senior lab manager Chris Myers. Together they created a customized prosthetic hand based on a mold of Sophie’s hand (prosthetic hands are not commonly customized for a particular hand). Lim then went one step further and made the prosthetic hand more glove-like by combining lightweight thermoplastic polymers with Velcro, foam padding, metal fasteners, elastic cord, and Kevlar string.
“Sophie’s Super Hand motivated us to look further into functionality because Sophie wanted to play on a jungle gym,” says Agogino.
Agogino and O’Connell teamed up with Sanjay Joshi, a professor of mechanical and aerospace engineering at UC Davis, to expand on Sophie’s Super Hand. Joshi specializes in Electromyography (EMG) technology, which involves a sensor that reads electrical output from muscles. The team started the “Million Hands” project to make prosthetic hands scalable to apply to millions of children at low-cost, and customizable for individuals with different hand shapes.
The Million Hands project was awarded CITRIS seed funding in 2017 and continued with six M.Eng students and two PhD students over the last year. Berkeley alumnus and philanthropist Dennis Chan has pledged to support the effort for four years. O’Connell’s “Designing for the Human Body” course, which includes a project to make a 3D-printed hand and redesign it for functionality, is also supported by Chan. With this funding, the project is able to continue through 2018-19 with a team of five M.Eng students and a PhD student.
The team published a peer-reviewed paper, “Customization of a 3D Printed Prosthetic Finger Using Parametric Modeling,” in the proceedings of the ASME (American Society of Mechanical Engineers) International Design Engineering Technical Conferences this summer, where they demonstrated how to scale prosthetic hands for different hands shapes easily.
Mechanical engineering PhD student Tomas Georgiou, a member of the Million Hands team, talks about two avenues he wants to pursue. “The first is utilizing parametric modeling in hand-prosthesis designing so that the model matches the user’s unique dimensions more closely and automatically scales,” says Georgiou. “The second has to do with developing functionally-specific prostheses for playing drums. The goal is to create an effective replication of finger and wrist function to improve user control, dexterity, and overall ability for musical expression.”
Agogino says that each individual has a unique hand and may need multiple prosthetics for different applications such as playing guitar, hanging on a jungle gym, or dancing. The team’s vision is to create an open-source online platform that has a database of all prosthetic hands, where each customer can get their best combination for both aesthetics and functionality. It would be an AI-enabled platform, says Agogino. “Pick the best one for a new person coming in, use artificial intelligence to select the right base case, and then refine it and customize for a particular individual,” she says.
The team has been collaborating with prosthetists at the Department of Orthopaedics at UCSF and UCSF Benioff Children’s hospitals in San Francisco and Oakland. Associate Dean of Children’s Health of UCSF Benioff Children’s Hospital Oakland Bertram Lubin (also a Berkeley Engineering advisory board member) has assisted with the collaboration to help the team better understand the users and the issues they face.
The project has received great support around campus. Berkeley’s Girls in Engineering (GiE) summer program ran a session including assembling prosthetic hands in 2016. This year, the Million Hands team was profiled by the Coleman Fung Institute for Engineering Leadership as part of a capstone project. The team further developed their idea by participating in the “Global Product Development” course at the Jacobs Institute for Design Innovation, which teaches how to transform prototypes into commercial products.
In addition, Million Hands prototypes were displayed for a month at the Lawrence Hall of Science (LHS) this summer as part of an “Ingenuity Challenges” exhibit, where visitors of all ages solve real world problems by using their ingenuity to build and test their own designs. The CITRIS Invention Lab provided prosthetic hands and a portable 3D printer that printed sample prosthetic fingers. “The hope is that not only can visitors see actual 3D-printed prosthetics happening, but they also see how cheap and easy is to provide them,” says Dan Chapman, senior artist at CITRIS.
“This is a great activity to inspire and promote science learning, and to help visitors see themselves as engineers while building empathy for others who don’t have hands or are born without limbs,” says Celia Castillo, manager of Ingenuity Challenges at LHS.
The collaboration between the CITRIS Invention Lab and LHS has provided an outlet for the team to show their work to the public. “People who aren’t associated with the university also come here to have fun with their families,” says John Ito, LHS production studio shop superintendent. “It’s a great way to connect beyond the academic community.”