Smart materials & tribology
Adaptive-Traction MREs
A smart material whose grip increases exactly when you press on it — passive, battery-free traction, starting with one of the most dangerous moments of the day: the shower.
Status: validated material + custom test rigThe problem
For someone with a leg prosthetic, bathing is one of the most dangerous moments of the day. To shower, they take the shoe off the prosthetic — and the instant the shoe comes off, so does their traction. Now they’re standing on a smooth, bare prosthetic foot on a wet, slick floor, often with nothing to hold onto. A clinician at a major prosthetics provider confirmed this is a real, largely unaddressed risk.
How it works
Magnetorheological elastomers (MREs) are smart materials whose stiffness can change. We 3D-print carbonyl-iron particles into a flexible elastomer and align them with a magnetic field during printing, forming internal columnar structures. When body weight presses on the material, those structures stiffen and surface friction rises; lift the weight, and it releases — no batteries, no electronics, nothing for the user to remember.
Passive activation
Grip engages from body weight alone — the key novelty, eliminating the electromagnetic activator that industry cites as the main barrier to commercializing MREs.
Tuned formulation
Across hundreds of in-house trials analyzed with a linear mixed model, a ~10%-iron-by-weight formulation gave the highest, most consistent grip across dry, dusty, and wet surfaces.
Built-from-scratch testing
With no lab tribometer available, the friction-testing rig was built from a deconstructed 3D printer to apply and measure controlled lateral force.
The process
How it was built
BUILD LOG — FORMULATIONS TESTED
Carbonyl-iron concentrations of 10%, 15%, and 20% by weight were printed and tested on a custom friction rig. 10% Fe was the measured optimum — the highest, most consistent grip across dry, dusty, and wet surfaces; above ~10% the magnetic effect reverses.
- MATERIAL
- Carbonyl iron in UV resin
- ALIGNMENT
- Magnetic field during print
- TEST RIG
- built from a 3D printer
- ANALYSIS
- linear mixed model · 100s of trials
- STATUS
- validated · pending lab x-val
Where it stands
The friction results are measured and statistically significant — but they currently rest on a test rig built in-house. We treat them as promising in-house findings pending independent validation, not finished claims. The most credible next step is cross-validating the friction data on wet surfaces against a calibrated laboratory tribometer.
The first target application is a thin MRE layer on the sole of a prosthetic foot that grips the instant the user steps onto a wet floor — the same passive mechanism, applied to a high-stakes problem with a clinical champion who has confirmed the need.
What’s next
- Independent wet-surface cross-validation of the friction data against a calibrated lab tribometer.
- Fabrication and shower-condition testing of a first prosthetic-sole prototype.
- Customer-discovery interviews with prosthetists and prosthetic users to document clinical demand.
- An SBIR/STTR proposal to the NIH STTR omnibus, partnered with a university mechanical-engineering lab.
Research prototype
This is an early-stage research prototype developed for engineering study and grant applications. It is not available for sale, has not been cleared or approved by the FDA, and performance results to date are from in-house testing pending independent validation. Nothing here is medical advice. Friction figures cited here are in-house measurements from a custom-built rig, pending independent laboratory cross-validation.