Direct-write formation of integrated bottom contacts to laser-induced graphene-like carbon.

We report a simple, scalable two-step method for direct-write laser fabrication of 3D, porous graphene-like carbon electrodes from polyimide films with integrated contact plugs to underlying metal layers (Au or Ni). Irradiation at high average CO2laser power (30 W) and low scan speed (∼18 mm s)-1leads to formation of 'keyhole' contact plugs through local ablation of polyimide (initial thickness 17µm) and graphitization of the plug perimeter wall. Top-surface laser-induced graphene (LIG) electrodes are then formed and connected to the plug by raster patterning at lower laser power (3.7 W) and higher scan speed (200 mm s)-1. Sheet resistance data (71 ± 15 Ω sq.)-1indicates formation of high-quality surface LIG, consistent with Raman data which yield sharp first- and second-order peaks. We have also demonstrated that high-quality LIG requires a minimum initial polyimide thickness. Capacitance data measured between surface LIG electrodes and the buried metal film indicate a polyimide layer of thickness ∼7µm remaining following laser processing. By contrast, laser graphitization of polyimide of initial thickness ∼8µm yielded devices with large sheet resistance (>1 kΩ sq.)-1. Raman data also indicated significant disorder. Plug contact resistance values were calculated from analysis of transfer line measurement data for single- and multi-plug test structures. Contacts to buried nickel layers yielded lower plug resistances (1-plug: 158 ± 7 Ω , 4-plug: 31 ± 14 Ω) compared to contacts to buried gold (1-plug: 346 ± 37 Ω , 4-plug: 52 ± 3 Ω). Further reductions are expected for multi-plug structures with increased areal density. Proof-of-concept mm-scale LIG electrochemical devices with local contact plugs yielded rapid electron transfer kinetics (rate constantk0 âˆ¼ 0.017 cm s-1), comparable to values measured for exposed Au films (k0 âˆ¼0.023 cm s)-1. Our results highlight the potential for integration of LIG-based sensor electrodes with semiconductor or roll-to-roll manufacturing.

Visually augmented targeted combination light therapy for acne vulgaris: a case report.

BACKGROUND: Acne vulgaris is a common skin disease. Pharmacological modalities for treatment are proven to be efficacious but have limitations. Light therapy for acne vulgaris has shown promise in previous studies. This case report and its accompanying images show how a novel approach of visually augmented high fluence light therapy has been used to good effect. CASE PRESENTATION: A 26-year-old Caucasian woman with acne vulgaris resistant to treatment with topical therapy underwent three sessions of combination potassium titanyl phosphate laser (532 nm)/neodymium-doped: yttrium aluminum garnet laser (1064 nm) light therapy with visually augmented narrow spot size and high fluence. A 73% reduction in total inflammatory lesions was evident 6 months after the initial treatment. CONCLUSIONS: This case report illustrates that there may be utility in this novel approach of narrow spot size, magnification-assisted, high fluence targeted combination laser therapy for inflammatory acne.

Asymmetric Pentagonal Metal Meshes for Flexible Transparent Electrodes and Heaters.

Metal meshes have emerged as an important class of flexible transparent electrodes. We report on the characteristics of a new class of asymmetric meshes, tiled using a recently discovered family of pentagons. Micron-scale meshes were fabricated on flexible polyethylene terephthalate substrates via optical lithography, metal evaporation (Ti 10 nm, Pt 50 nm), and lift-off. Three different designs were assessed, each with the same tessellation pattern and line width (5 µm), but with different sizes of the fundamental pentagonal unit. Good mechanical stability was observed for both tensile strain and compressive strain. After 1000 bending cycles, devices subjected to tensile strain showed fractional resistance increases in the range of 8-17%, while devices subjected to compressive strain showed fractional resistance increases in the range of 0-7%. The performance of the pentagonal metal mesh devices as visible transparent heaters via Joule heating was also assessed. Rapid response times (∼15 s) at low bias voltage (≤5 V) and good thermal resistance characteristics (213-258 °C cm2/W) were found using measured thermal imaging data. Deicing of an ice-bearing glass coupon on top of the transparent heater was also successfully demonstrated.