Iris Ritsma


A below knee prosthesis that mimics the human gait



A problem in the current segment of below knee prosthetics is that the available prosthetics in the lower price segment lack functionality, however prosthetics with advanced functionality, like bionic feet, are too expensive for most users and not covered by insurances.The aim of our project was to design an affordable modular below-knee prosthesis that allows users to experience their active daily life with minimal concessions.





Arcx is an innovative prosthetic foot that mimics the human gait and combines functions that are currently only seen in separate products. The design makes an active lifestyle possible by providing an adjustable ankle hinge, enabling both running and walking, giving extra comfortable sideways stability and adding options for personalisation.




University: Delft University of Technology
Year: 2017

Patent NL2020034

Team: Francis Folkers, Stijn Jagers op Akkerhuis, Donovan Lewis, Iris Ritsma, Thomas Zwart, Clément Heinen

The James Dyson Award national runner up


Design question

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“How might we design an affordable below-knee prosthesis that allows the user to experience their daily active life with minimal concessions.”


The problem

The design has been inspired by observing active users in their daily life, noticing that they are held back by their current prosthetics or carry around an extra prosthesis to be able maintain their active lifestyle. We saw that especially for young children the current segment does not suffice. because they are growing they need multiple prosthesis within short amounts of time, this results in them not being to afford more expensive prosthetics. On top of that they even need to buy a separate one for doing sports. When going to school they are not able to take a little sprint or to play football with their friends because the "walking prosthetic" is not made for such activities. 

Another important aspect in the design process was designing for the total product experience. As the prosthesis really becomes a part of the user’s body the aesthetics have a huge influence on how the product is experienced. The looks of prosthetics have stayed the same for many years, in order to make them fit in a shoe they get a rubber cover that mimics a human foot, unfortunately it rather looks scary an lifeless.




90 degrees

The foot is locked in an angle of 90 degrees


2 Prosthetics

For an active lifestyle two separate prosthetics are needed



Current prosthetics mimic human feet, which results in a scary lifeless piece of rubber

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Diving into the ergonomics of the human body

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Customer Journey Analasys

Together with Clement Heinen I analyzed the customer journey of living one day with a prosthesis



Rapid Prototyping

Testing basic working principles with 3D printed models

Using rapid prototypes basic principles were tested. These prototypes evolved from simple paper and cardboard models into 3D printed prosthetic feet that each were designed to test different innovations. The 3D printed prototypes have been tested to see how their energy is stored and relieved during gait and to test their stability using a pull-out couch. Also the ankle hinge was tested for ergonomics and safety. 


Each of the prototypes was designed to test a different innovation, these prototypes evolved from simple paper and cardboard models into 3D printed prosthetic feet


Final prototype


“the final prototype was split up in an aesthetic model and a custom made prototype for our end user to test.”

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The prototyping process

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User validation

I have been in charge of setting up an evaluation session of the final design with the end user. I defined the tests that needed to be carried out with both the aesthetic prototype and the functional prototype. 

Due to portrait rights we are unfortunately not able to depict the user's face.

"This feels like a liberation, it has been 15 years since I was able to sit normally"

"This feels like a liberation, it has been 15 years since I was able to sit normally"



Advantages of arcx


Walk & Run

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Ankle Freedom

Sideways Stability