Innovative Smart Material Solidifies When Bent or Twisted

Iowa State University engineers, Michael Bartlett and Martin Thuo, have developed a new reactive and smart material that can solidify like a muscle after it has worked out.

According to the engineers whose research appears in the Materials Horizons scientific journal, when a muscle is stressed, it tautens up. Their rubbery material similarly responds to mechanical stress, such as bending or twisting it, by spontaneously hardening by up to 300%. In their laboratory trials, such pressures converted a malleable band of the material into a solid compound that is able to sustain 50 times its own mass.

Moreover, this innovative material does not require external sources of energy like light, electricity, or heat to alter its properties. It can be utilized in various ways, such as for industrial applications (e.g. to safeguard important sensors) and medical (e.g. to support delicate tissues) applications.

The paper’s lead authors Bartlett and Thuo, assistant professors of materials science and engineering at Iowa State, received the University’s startup funds to develop the innovative material. The project was also helped via Thuo’s faculty fellowship at global leading EPC company, Black and Veatch.

The material’s creation comes out of a great amalgamation of Thuo’s proficiency in liquid-metal, micro-sized particles and Bartlett’s expertise in lenient materials such as plastics, gels, and rubbers.

The researchers created a cheap and easy way to harvest tiny undercooled metal particles — metal which stays liquid even when it reaches below the temperature at which it melts. The particles are formed by allowing drops of melted metal to come into contact with O2, generating a corrosion layer that covers the drops and prevents the liquefied metal from solidifying. They also managed to merge these particles with a rubbery elastomer material without damaging them.

When this fusion material is subjected to stresses —squeezing, twisting, bending, or pushing — the liquid-metal elements pops open. The metal runs out of the oxide casing, merges and congeals resulting in a mesh of metal that develops within the material. The point of popping can be tailored by using different metal, altering the sizes of the particles, or by switching the supple material.

The new smart material could be used in malleable and bio-stimulated automation or wearable and reconfigurable electronics. The Research Foundation of Iowa State is working on patenting the material and it is obtainable for licensing.