Oh, patents! The SoftFoot Pro, a motorless robotic foot.

 Copyright © Françoise Herrmann

Designed at the Italian Institute of Technology (Istituto Italiano di Tecnologia), the fully passive (motorless), anthropomorphic and flexible SoftFoot Pro was invented to improve the state of the art in prosthetic feet, preferably fitted to a human limb, but also compatible with a humanoid robot. Specifically, the Softfoot Pro was designed to remedy the incidence of falls among lower limb prosthetic users (LLPUs), 50% of whom experience falls at least once a year, resulting in additional injury (Pace, A., Dimitrov, H., Jakubowitz, E. et al. (2026). 

Indeed, according to the inventors, the prior art of prosthetic feet is generally too rigid and/or heavy to readily negotiate uneven or rugged terrain. In turn, stepping on obstacles risks destabilizing and altering the LLPUs’ gait, invoking a fall or long-term sequela such as osteoarthritis. Surface obstacles also place an extra burden on the cognition of LLPUs in the effort to alter their stride, and the extra attention required to successfully negotiate uneven-surface hurdles. Thus, the SoftFoot Pro was created to conform to uneven surfaces, even slippery ones. Ultimately, the SoftFoot Pro was designed to respond to any surface, while creating a comfortable and easy stride for LLPUs, and minimizing cognitive stress. Because of its designed anthropomorphic flexibility, emulating the tarsus, metatarsus, and phalanges skeletal anatomy, as well as the plantar fascia, the SoftFoot Pro also facilitates the performance of everyday tasks, such as bending on one knee to tie a shoelace.

The SoftFoot Pro invention is recited in the World Intellectual Property Office (WIPO) patent WO2026003774A1, titled Robotic foot. The patent was awarded on February 1st, 2026, to seven inventors: Antonio Bicchi, Manuel Giuseppe Catalano, Giorgio Grioli, Manel  Barbarossa, Emanuele Sessa, Anna Pace and Matteo Crotti. The joint applicants were Fondazione Istituto Italiano Di Tecnologia, in Genoa, Italy, and the Università Di Pisa, in Italy. 

Below, the patent Figure 1 depicting a perspective view of the SoftFoot Pro (1), together with the Abstract of the invention, indexing the drawing. In a nutshell, the patent Figure 1 depicts the titanium mobile arch system (4) of the foot (1), with a hinge (6), defining a rotational axis, and connected to a joint (2), receiving the fitted human limb or humanoid device. The arch system (4) is connected to five parallel plastic chains, forming a surface contact organ (3). Each of the parallel plastic chains is made of high-strength automotive plastic modules, each connected via an inextensible transversal cable, attached at the heel (5) of the foot (1). The plastic chains have two rotational axes (3a) and (3b), with pairs of plastic links between each module. The inextensible cable system is meant to emulate the biomechanical windlass phenomenon, which stiffens the fascia to stabilize the arch by evenly distributing forces to the ground, whereas the plastic links provide flexibility to the modules, also functioning as shock absorbers. 

A foot (1) is configured to rest on a walkable surface (1b) and comprising: a joint (2) to a prosthesis (1a); a contact organ (3) defining a deformable contact area of the foot (1) with the walkable surface (1b); a first body (4) defining the frontal arch of the foot (1), a first end (4a) proximal to the joint (2) and an additional first end (4b); a second body (5) defining the heel of the foot (1), a second extremity (5a) proximal to the joint (2) and an additional second extremity (5b) distal to the attachment (2); an ankle hinge (6) defining a main axis (6a) of mutual rotation between the first body (4), second body (5) and joint (2) and interposed between both first extremities (4a, 4b) and second extremities (5a, 5b). The foot also involves the contact organ (3) connecting the additional ends (4b, 5b); and also first elastic means (7) and second elastic means (8) connecting the first end (4a) and second end (5a) to the joint (2), respectively.

[Abstract WO2026003774A1]

Below, the close-up image of a marketed SoftFoot embodiment, together with an Italian Institute of Technology (ITT) Youtube video. 

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References

Italian Institute of Technology (IIT)
https://www.iit.it/
IIT (07-11-2024). Introducing SoftFoot Pro: a cutting-edge motorless, flexible and waterproof artificial foot. Italian Institute of Technology.
https://opentalk.iit.it/en/introducing-softfoot-pro-a-cutting-edge-motorless-flexible-and-waterproof-artificial-foot/
Pace, A., Dimitrov, H., Jakubowitz, E. et al. (2026). The SoftFoot Pro: an anthropomorphic and adaptive soft articulated prosthetic foot. Nature Communications 17, 1459 (2026). https://doi.org/10.1038/s41467-025-68194-2
https://www.nature.com/articles/s41467-025-68194-2