Antimicrobial silicone skin adhesives facilitated by controlled octenidine release from glycerol compartments

For improved wound healing,antimicrobial adhesives are one path forward.However,with the current challenge of bacterial resistance,it is essential to choose the included drug carefully.Octenidine is an obvious choice due to its broad antimicrobial efficacy and no reported bacterial resistance.In its pure form,octenidine complexes efficiently with the platinum catalyst in the silicone composition,inhibiting the targeted hydrosilyla-tion reaction and hindering curing.This obstacle is overcome by screening octenidine with cyclodextrins in homogeneously dispersed glycerol droplets,suppressing Pt inhibition in the silicone phase.Curing efficiency is demonstrated using rheol-ogy,which shows that it is possible to incorporate one wt%of octenidine into glycerol–silicone adhesives in the presence of(2-hydroxypropyl)-β-cyclodextrin without affecting the adhe-sives’mechanical properties.The interaction between octeni-dine and(2-hydroxypropyl)-β-cyclodextrin through an inclusion complex is confirmed by ROESY spectroscopy.Despite this screening,octenidine is still released efficiently from the glycerol–silicone adhesives upon contact with water,and the resulting antimicrobial action is subsequently demonstrated.This new technology constitutes a simple and efficient method for preparing wound care adhesives that actively inhibit the growth of four bacteria strains and one fungus.

Stretchable Parylene-C electrodes enabled by serpentine structures on arbitrary elastomers by silicone rubber adhesive

The delicate serpentine structures are widely used in high-performance stretchable electronics over the past decade.The metal interconnects encapsulated in biocompatible polymer Parylene-C film is a superior choice for long-term implantation in vivo,especially as neural interface to acquire electrophysiological signals or apply electrical stimulation.To avoid the physical contact damages from the neural tissues such as the brain or peripheral nerves,serpentine interconnects are utilized as stretchable electrodes and usually bonded to the soft elastomer substrate.The adhesion strength between the serpentine interconnects and the elastomer substrate becomes a considerable issue to ensure reliability and structural integrity.In this paper,the stretchable Parylene-C electrodes can be transfer printed onto arbitrary elastomer substrates by a thin layer of silicone rubber adhesive with low modulus for electrocorticogram(ECoG)recording.Mechanical simulation of serpentine structures consisting of same periodic arcs and different straight segments is investigated by uniaxial stretching.Then,the elastic stretchability of serpentine electrodes is further studied by simulation and experiments.After 5000 repetitive stretching cycles,the electrochemical impedance of microelectrodes remains in steady states.These results prove that the silicone rubber adhesive facilitates the interfacial bonding in the structure of stretchable electrodes as the compliant and reliable neural interface.

Investigation of hybrid microring lasers adhesively bonded on silicon wafer

Thermal characteristics are numerically investigated for the hybrid AlGaInAs/InP on silicon microring lasers with different ring radii and widths. Low threshold current and low active region temperature rise are expected for a microring laser with a narrow ring width. Based on the thermal analysis and the 3D simulation for mode characteristics, a hybrid AlGaInAs/InP on silicon microring lasers with an inner n-electrode laterally confined by the p-electrode metallic layer is fabricated using an adhesive bonding technique. A threshold current of 4 mA is achieved for a hybrid microring laser with a radius of 20 μm and a ring width of 3.5 μm at 12°C, and the corresponding threshold current density is as low as 1 kA∕cm^2. The influence of the location of silicon waveguide on output performance is studied experimentally for improving the output coupling efficiency. Furthermore,continuous-wave electrically injected lasing up to 55°C is realized for a hybrid microring laser with a radiusof 30 μm and a ring width of 3 μm.