Available at: https://digitalcommons.calpoly.edu/theses/3426
Date of Award
8-2026
Degree Name
MS in Biomedical Engineering
Department/Program
Biomedical Engineering
College
College of Engineering
Advisor
Eric Espinoza-Wade
Advisor Department
Mechanical Engineering
Advisor College
College of Engineering
Abstract
Upper-limb loss can significantly impact overall quality of life by limiting a person's ability to perform activities of daily living (ADLs). Although prosthetic devices can help bridge the gap, many upper-limb prostheses are limited by high costs, discomfort, limited repairability, and accessibility barriers. Current commercial myoelectric prosthetic hands can provide high levels of functionality, but are often expensive and require specialized clinical access. In contrast, many current low-cost and open source prosthetic devices improve affordability but are limited in function or designed for partial hand applications rather than full transradial limb loss.
The purpose of this thesis was to design, fabricate, and evaluate a low-cost modular transradial prosthetic system consisting of two interchangeable hand effectors with different functional capabilities. The first hand effector, The Dexter Hand, was designed to focus on dexterity and performing a broad range of grasp patterns. The design included features such as finger adduction/abduction in order to improve its ability to perform grasp patterns from the Cutkosky Taxonomy. The second hand effector, The Heavy Duty Hand, was designed to prioritize lifting capacity and performing strength-focused grasps. Both hand effectors were designed to connect to a shared transradial platform using a modular attachment interface.
The system was developed using 3D printed components, common hardware, and powered actuation in order to support the goals of low-cost, repairability, and accessibility. Evaluation of the devices involved the Dexter Hand’s ability to perform grasp patterns representative of daily task activities, the Heavy Duty Hand’s ability to lift heavier objects, and the modular platform’s ability to support quick and seamless interchangeability between hand effectors. Overall system level evaluations also included cost, weight, durability, repairability, and battery life. The Dexter Hand successfully completed 13 of 16 Cutkosky grasp patterns, the Heavy Duty Hand completed eight of nine Cutkosky power grasp patterns and supported a maximum load of 7.72 lb for 30 seconds, and the hand effectors were exchanged in an average of 7.28 seconds.
This design demonstrates a modular approach to balancing dexterity and strength in a low-cost transradial prosthetic system. Rather than relying on a single hand to perform all tasks, the proposed system separates and optimizes dexterity and strength functionality in different hand effectors. This approach provides a potential pathway toward more accessible, repairable, and task specific upper-limb prosthetic devices.