pruning of disordered networks*

The mechanical properties of disordered networks can be modified by pruning bonds in order to achieve a variety of unconventional responses [1,2]. For example, one can generate a long-range ‘allosteric’ response so that a localized input strain at one site produces a strain at a predetermined distant target. Previous work has relied on computer simulations that use a cost function to design in such functionality. Here we show that we can determine which bonds to prune using experiment alone without any computer intervention. We build networks out of photoelastic material and observe them between crossed polarizers. By measuring the stresses in the bonds under various applied strains, we can identify which ones to prune in order to achieve a specific desired response. This approach uses only local stress information without the necessity of a cost function and does not involve computer simulation. We have been able to design networks with allosteric responses at a high success rate by pruning a small fraction of the bonds.
[1] JW Rocks, N Pashine, et al. PNAS 114, 2520–2525 (2017).
[2] DR Reid, N Pashine, et al. PNAS 115, E1384-E1390 (2018).