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A system was built to test the efficacy of bacterial biofilm disruption using laser generated shockwaves. The system is based on a Q-switched, ND:YAG pulsed laser operating at a rep rate of 10 Hz with 1500 mJ pulses centered at 1064 nm. The laser pulses were used to create shockwave pulses in Al coated polycarbonate substrates and a resulting peak stress of greater than 50 MPa was measured. These stress pulses were coupled to bacteria grown to confluence on agar plates and cell death as a result of shockwave stress was assessed. The results show a 55% reduction in the number living bacteria between shocked and control samples. This type of biofilm disruption method could prove useful in the treatment of infected wounds where standard treatment methods such as debridement and topical antibiotics have proven to be ineffectual or harmful.

Preliminary investigation into the safety of the LGS treatment for biofilm delamination appears promising. Additional investigation will continue on ex vivo porcine samples, followed by an in vivo animal trial to better understand the physiological response to LGS treatment.

An experimental study to bend FIB-prepared cantilevered single crystal Cu nanopillars of several hundred nanometers in diameter and length at ultrahigh strain rate is presented. The deformation is induced by laser-generated stress waves, resulting in local strain rates exceeding 10 7 s À1 . Loading of nano-scale Cu structures at these extremely short loading times shows unique deformation characteristics. At a nominal stress value of 297 MPa, TEM examination along with selected area electron diffraction characterization revealed that twins within the unshocked Cu pillars interacted with dislocations that nucleated from free surfaces of the pillars to form new subgrain boundaries. MD simulation results were found to be consistent with the very low values of the stress required for dislocation activation and nucleation because of the extremely high surface area to volume ratio of the nanopillars. Specifically, simulations show that the stress required to nucleate dislocations at these ultrahigh strain rates is about one order of magnitude smaller than typical values required for homogeneous nucleation of dislocation loops in bulk copper single crystals under quasi-static conditions. V C 2013 AIP Publishing LLC. [http://dx.