In a world of smart ‘things,’ why not self-sorting socks?

Originally published 9 March 1992

Wel­come to the age of smart materials.

A new alliance of engi­neers, chemists, physi­cists, and com­put­er experts are work­ing to endow mate­ri­als such as con­crete and met­al with “ner­vous sys­tems” and “intel­li­gence.” And they are cre­at­ing new struc­tur­al mate­ri­als as sub­tly respon­sive to their envi­ron­ment as the skin of a dol­phin or a but­ter­fly­’s wing.

Today’s air­planes have un-smart skins of sheet met­al. The smart plane of the future will be clothed in a mul­ti-lay­ered com­pos­ite mate­r­i­al with built in “nerves” and “mus­cles.” Embed­ded fiber-optic threads will mon­i­tor the skin for micro-cracks or dan­ger­ous stress­es. Elec­tron­ic cir­cuits built into the skin will process infor­ma­tion on-the-spot from the fiber-optic net­work. Mil­lions of tiny pres­sure-sen­si­tive actu­a­tors will respond by stiff­en­ing the skin or damp­ing out vibrations.

A smart air­craft skin might also incor­po­rate bil­lions of tiny vac­u­um pores that open and close in response to the flow of air over the skin, cor­rect­ing for tur­bu­lence that might decrease the fuel effi­cien­cy of the plane — or cause an accident.

Or imag­ine con­crete for a bridge with its own “immune sys­tem,” chem­i­cals that detect and respond to weath­er­ing of the con­crete or cor­ro­sion of rein­forc­ing rods. Imag­ine con­crete thread­ed with fibers filled with adhe­sive; if a crack devel­ops in the con­crete, the fibers rup­ture and release a crack-seal­ing glue.

The goal of “smart-mate­ri­als” researchers is to ani­mate the inan­i­mate world. They now have their own pub­li­ca­tion, The Jour­nal of Intel­li­gent Mate­r­i­al Sys­tems and Struc­tures. This month Japan hosts the First Inter­na­tion­al Con­fer­ence on Intel­li­gent Mate­ri­als. In May, the First Euro­pean Con­fer­ence on Smart Struc­tures & Mate­ri­als will be held in Scotland.

Smart struc­tures. Intel­li­gent mate­ri­als. They are hot, they are fad­dish, they are the future.

As long as all these clever sci­en­tists and engi­neers are putting their heads togeth­er to endow bridges and air­planes with ani­ma­tion and self-aware­ness, let me sug­gest a few smart prod­ucts I’d like to see.

Snow-No-More Dri­ve­way Com­pound. An asphalt-based mate­r­i­al that stores up solar ener­gy chem­i­cal­ly dur­ing the sum­mer, by a kind of pho­to­syn­the­sis, and releas­es the ener­gy as heat when trig­gered by the appro­pri­ate com­bi­na­tion of cold and mois­ture. No more shoveling.

TidyTable Din­ner­ware. Dish­es that can be acti­vat­ed — say, by a loud clap — to clean them­selves. Food soil would be detached, bro­ken up, and dis­persed as harm­less gas­es by tiny, sur­face-embed­ded nanoro­bots. Like anti­bod­ies in the human immune sys­tem, these nanoro­bots would rec­og­nize any mate­r­i­al that is not self, and attack. Dish­es would nev­er leave the table and would always be sparkling clean.

Sun-‘n‑Shade Roof­ing Sys­tem. Sure­ly, no mate­r­i­al is more in need of an intel­li­gent replace­ment than the stan­dard Amer­i­can roof­ing shin­gle. What we require is a smart mate­r­i­al that changes col­or with the sea­son, becom­ing reflec­tive in sum­mer and absorp­tive in win­ter, cool­ing or heat­ing the house appro­pri­ate­ly. A net­work of cap­il­lar­ies embed­ded in the mate­r­i­al would sup­port a solar hot water sys­tem, and might even allow the house to cool itself by sweat­ing dur­ing hot weather.

Spring­back Cot­ton. This fab­ric would incor­po­rate threads of niti­nol, a nick­el-tita­ni­um alloy that remem­bers its shape. Below a cer­tain tem­per­a­ture, niti­nol will take any shape it is bent into, but when heat­ed returns to its orig­i­nal shape. Heat­ed in a clothes dri­er, Spring­back cot­ton will “spring back” into its orig­i­nal, unwrin­kled state. No iron­ing will be nec­es­sary. At last, we’ll have the com­fort and feel of cot­ton with the con­ve­nience of polyester.

Elec­tro-Floor. A floor­ing mate­r­i­al incor­po­rat­ing a piezo­elec­tric poly­mer such as polyvinyli­dene flu­o­ride. These mate­ri­als con­vert mechan­i­cal pres­sure into elec­tric­i­ty. My wife com­plains that I am always ner­vous­ly pac­ing around the house. By con­nect­ing the Elec­tro-Floor car­pet to stor­age bat­ter­ies, my pac­ing will gen­er­ate use­ful ener­gy. Even the cat’s noc­tur­nal ambu­la­tions will help cut the elec­tric bill.

Lus­tra­Bowl Toi­lets. No house­hold chore is more unpleas­ant than clean­ing the toi­let. A toi­let bowl whose inte­ri­or sur­face was coat­ed with piezo­elec­tric ceram­ic could be elec­tri­cal­ly stim­u­lat­ed to vibrate vig­or­ous­ly each time the toi­let is flushed, dis­lodg­ing soil, and, by impart­ing high-fre­quen­cy sound to the flush water, clean­ing the bowl ultrasonically.

Per­fect Rest Mat­tress. This foam mat­tress would be made of a poly­mer­ic gel that dilates or con­tracts when charged elec­tri­cal­ly or neu­tral­ized. Opti­cal fibers in the sur­face of the mat­tress would sense every twist and turn of the sleep­er’s body and send this infor­ma­tion to a micro­com­put­er embed­ded in the mat­tress. The com­put­er would con­trol a net­work of elec­trodes stim­u­lat­ing the poly­mer gel, reg­u­lat­ing the firm­ness of the mat­tress with infi­nite sub­tle­ty. Com­fort would be max­i­mized for each part of the body, and, in the case of a dou­ble bed, firm­ness could be cus­tomized for each sleep­er independently.

Chameleon Brand Footwear. Socks made of this mate­r­i­al would sort them­selves out in the draw­er by chang­ing col­or to match their mate, and retain their col­or when they are worn. In an age of smart mate­ri­als, no one should have to go to work with mis­matched socks.