Pointdexter: A Prosthetic Fingertip Terminal Device

Period of Performance: 09/21/2016 - 04/29/2017


Phase 1 SBIR

Recipient Firm

Liberating Technologies, Inc.
Principal Investigator


Project Summary Modern dynamic upper limb prosthetic terminal devices tend to either be functional or cosmetic, with most common designs making compromises between both aspects. Prosthetic hooks and grippers are particularly good at grasping a variety of objects but are not cosmetic. Conventional electric hands are more cosmetic, but do not allow for conformal grasp or multiple grasp patterns and have difficulty grasping small objects. Multi- articulating hands are also cosmetic, can conform to larger objects that are grasped, and offer multiple grasp patterns. However, multi-articulating hands still have difficulty grasping and manipulating smaller objects. As no single terminal device meets all of the criteria of an ideal terminal device, users often have to physically remove and don different terminal devices to achieve the variety of tasks that they need to perform in their activities of daily living (ADLs). The proposed solution aims to combine the advantages of the common terminal devices into one solution, by combining the practicality and dexterity of a split-hook or gripper with the aesthetics of multi- articulating hands. The primary objective of the proposed project is design, develop and test a novel terminal device. Design criteria related to size, grasping force, etc. will be generated and refined as iterations of the device are created. The ability of the device to meet the design criteria will be verified through bench top testing. The device will then be tested with a small sample of amputee end-users using clinically validated outcomes measures. These pilot tests will evaluate the feasibility of the device, demonstrate improvements in function, and drive further development. Feedback from both amputees and clinicians will also be solicited to guide future design iterations. The proposed terminal device would allow amputees more utility from their prosthesis in tasks requiring fine grasping with two hands, such as in tying shoes or in work activities, such as manufacturing small components. All users would be able to have the best aspects of fine-motor control, the existing gross function, and cosmetic appeal in a single terminal device.