University of Washington Ability & Innovation Lab (https://depts.washington.edu/uwsteele/)

This is an example of an adjustable stiffness ankle foot orthosis (AFO) which can be tuned with different sizes of elastic polymer bands. This AFO model was used for evaluating how different dorsiflexion resistance impacts musculotendon function and walking pattern using ultrasound, musculoskeletal modeling (OpenSim) and motion capture system.  

Description about AFO:

• This ankle foot orthosis uses commercially available metal hinge joints (Camber Axis Hinge, Becker). 
• Two elastic polymer band supports can be placed on the shank and the foot segment. Overlap area can be trimmed out using 3D mesh design tool such as Meshmixer.
• Elastic polymer band mold can be fabricated with the positive mold which is provided in the attached file. Using the positive 3D printed mold, fabricate the negative mold with silicon material (OOMOO 30, Smooth-On). After curing, the negative silicon mold can be used to create an elastic polymer band with any type of material.
• Different thickness of RubberBand_Stopper can be used for adjusting elastic polymer band position on the elastic polymer band support. This allows changing AFO stiffness with single elastic polymer band by changing moment arm of the elastic polymer band. 

More detailed fabrication instruction and purpose of the AFO model can be found the journal paper titled "Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait" in Journal of Biomechanics. Additional detailed references will be updated after publication.