Flexible artificial foot mimics human movement, can help people with limb loss

Italian Institute of Technology (IIT) takes prosthetics to the next level with SoftFoot Pro. This prosthetic foot has been designed to move and adapt like a natural human one.

This unique foot is motor-free, flexible, and designed for all-weather use. It draws inspiration from the human foot, emulating its shape and anatomical features.

The SoftFoot Pro prototype made its grand public debut at a G7 Health track event in Genoa, Italy. This technical event, organized by the Italian Ministry of Health in collaboration with IIT, focused on strategies for lifelong health and active aging.

“What prostheses and today’s humanoid robots have in common is the characteristic of having flat or low compliant feet, developed to ensure maximum stability but incapable of adapting to changes in terrain contour, slope, and different positions such as kneeling or bending,” said Manuel G. Catalano, a researcher in the Soft Robotics for Human Cooperation and Rehabilitation Lab at IIT.

Mimics human foot

SoftFoot Pro provides a two-in-one solution. This concept improves movement and balance for patients with limb loss, while also opening the way for more nimble and adaptive humanoid robots for traversing various terrains.

Traditional prosthetics may struggle on uneven terrain. SoftFoot Pro’s flexible design changes shape to adapt to any surface, slippery or rough, for improved stability and a more natural walking experience.

Interestingly, the artificial foot is lightweight, weighing around 450 grams, yet can comfortably support up to 100 kg of users. The SoftFoot Pro design uses new materials to recreate the major components of the human foot’s anatomy.

The foundation is a movable arch composed of titanium for maximum strength (or a lightweight yet powerful aluminum alloy). This arch links to five parallel chains composed of a unique, high-strength plastic that resembles the plantar fascia in the human foot and allows for natural mobility. Plantar fascia is a tissue band that connects the heel bone to the toe base.

This unique chain system enables the foot to replicate the “windlass mechanism” of the human foot. This process stimulates the tightening of the plantar fascia when walking, resulting in a balanced pressure distribution on the ground. These chains are strung with a high-performance, ultra-durable cable measuring 210 millimeters from heel to toe.

“The arch system and the elastic chains constitute the artificial equivalent of the architecture composed by tarsus, metatarsus, and phalanges of the human foot,” the press release mentioned.

Conquer any terrain

Its flexibility allows for everyday actions like bending down, picking things up, climbing stairs, and making daily life easier.

Waterproof and adaptable, SoftFoot Pro can conquer any terrain, from meadows and beaches to slippery surfaces. Moreover, this artificial foot will enable users not to switch prosthetics for different activities.

“SoftFoot Pro can change its shape, allowing the foot sole to deform and to adapt to the roughness of the terrain and any obstacles, minimizing them, improving the naturalness of the step, and enhancing the stability of the user,” the press release described.

The innovative design of SoftFoot Pro is already patent-protected internationally, with two patents secured and a third under review by the European Patent Office.