In prisons, almost anything can be fashioned into a weapon. Razor blades, toothbrushes, padlocks and even bucket handles have been used in U.S. prisons as lethal weapons.
While some prisons have replaced toothbrushes with three-inch versions that slide onto a fingertip, others stick with more traditional, cost-efficient products.
Paul Biermann, an inventor at Johns Hopkins University's Applied Physics Laboratory, thinks that altering the molecular properties of everyday toiletries can make them functional, normal-size — and harmless.
At his lab in Laurel, Md., Biermann and a team of engineers have been working on a toothbrush that can't be filed down or melted. After rejecting several designs — including a toothbrush with a hollow handle filled with plastic balls — the team has invented a triple-layer toothbrush.
The epoxy core is encased in a hard urethane layer that is covered in a softer urethane shell. As the toothbrush's urethane material hardens, its molecular chains link to those closest to each other, rendering it resistant to reshaping.
Biermann is using the same material for shaver handles, and he has designed the blades to break into tiny pieces if prisoners remove them.