A laser-induced-graphene (LIG) pattern fabricated using a 355 nm pulsed laser was applied to a strain sensor. Structural analysis and functional evaluation of the LIG strain sensor were performed by Raman spectroscopy, scanning electron microscopy (SEM) imaging, and electrical–mechanical coupled testing. The electrical characteristics of the sensor with respect to laser fluence and focal length were evaluated. The sensor responded sensitively to small deformations, had a high gauge factor of ~160, and underwent mechanical fracture at 30% tensile strain. In addition, we have applied the LIG sensor, which has high sensitivity, a simple manufacturing process, and good durability, to human finger motion monitoring.

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PurposeTo investigate patients who had transrectal ultrasonography (TRUS)-guided prostate biopsy to define the role of the serum testosterone level in predicting prostate cancer risk and its association with a high Gleason score.Materials and MethodsA total of 568 patients who underwent prostate biopsy were entered in this study. We divided the patients into two groups according to serum testosterone level (median level, 3.85 ng/ml): the high-testosterone group (n=285) and the low-testosterone group (n=283). Multivariate regression analysis was used to define the effect of age, prostate volume, serum prostate-specific antigen (PSA) level and PSA density, and serum testosterone level on the risk of prostate cancer and a high Gleason score.ResultsBaseline characteristics did not differ significantly between the two groups. Compared with the high-testosterone group, the low-testosterone group had a significantly higher prostate cancer incidence (38.9% vs. 29.5%, p=0.018). Factors associated with an increased risk of prostate cancer were increased age (odds ratio [OR]=1.08, 95% confidence interval [CI]=1.25-3.16, p=0.001), a high serum PSA level (OR=3.35, 95% CI=2.63-4.25, p=0.001), a low prostate volume (OR=0.183, 95% CI=0.11-0.30, p=0.001), and a low serum testosterone level (OR=1.99, 95% CI=1.25-3.16, p=0.001). Among these, only the serum PSA level was a strong predictor of high-grade prostate cancer (Gleason score ≥7) (OR=2.19, 95% CI=1.57-2.95, p=0.001).ConclusionsPatients with lower levels of serum testosterone had a higher risk of prostate cancer than did patients with high serum testosterone. Even though a lower serum testosterone level was a predictor of prostate cancer risk, it was not associated with an increased risk of high-grade prostate cancer.

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Recently, semiconducting nanofiber networks (NFNs) have been considered as one of the most promising platforms for large-area and low-cost electronics applications. However, the high contact resistance among stacking nanofibers remained to be a major challenge, leading to poor device performance and parasitic energy consumption. In this report, a controllable welding technique for NFNs was successfully demonstrated via a bioinspired capillary-driven process. The interfiber connections were well-achieved via a cooperative concept, combining localized capillary condensation and curvature-induced surface diffusion. With the improvements of the interfiber connections, the welded NFNs exhibited enhanced mechanical property and high electrical performance. The field-effect transistors (FETs) based on the welded Hf-doped InO (InHfO) NFNs were demonstrated for the first time. Meanwhile, the mechanisms involved in the grain-boundary modulation for polycrystalline metal-oxide nanofibers were discussed. When the high-k ZrO dielectric thin films were integrated into the FETs, the field-effect mobility and operating voltage were further improved to be 25 cm V s and 3 V, respectively. This is one of the best device performances among the reported nanofibers-based FETs. These results demonstrated the potencies of the capillary-driven welding process and grain-boundary modulation mechanism for metal-oxide NFNs, which could be applicable for high-performance, large-scale, and low-power functional electronics.

We present the replication of polyethylene (PE) nano-micro hierarchical structures and their application for superhydrophobic surfaces. A commercial ultrasonic welding system was used to apply ultrasonic vibration energy to the forming of nano-micro hierarchical structures. To evaluate ultrasonic formability, Ni nanomold and nano-micro hierarchical mold were designed and fabricated. The optimal weld times were 1.5 s and 3.0 s for PE nanoprotrusions and nano-micro hierarchical structures, respectively. The forming process was conducted at atmospheric pressure. The PE structures were well replicated without a vacuum. The trapped air in the microcavity of the nano-micromold was dispersed and absorbed into the molten PE. Ultrasonic nano-microreplication technology showed an extremely short processing time and did not require a vacuum environment. To investigate the applicability of ultrasonic forming, the fabricated nanoprotrusions and nano-micro hierarchical structures were coated with plasma polymerized fluorocarbon (PPFC) of a hydrophobic nature and were applied to modify superhydrophobic surfaces. The contact angle was increased from 106 • (smooth surface) to 125 • (nanostructured surface) and finally to 160 • (nano-microstructured surface) so that the surface became superhydrophobic.

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The conversion of graphene oxide (GO) into reduced graphene oxide (rGO) is imperative for the electronic device applications of graphene-based materials. Efficient and cost-effective fabrication of highly uniform GO films and the successive reduction into rGO on a large area is still a cumbersome task through conventional protocols. Improved film casting of GO sheets on a polymeric substrate with quick and green reduction processes has a potential that may establish a path to the practical flexible electronics. Herein, we report a facile deposition process of GO on flexible polymer substrates to create highly uniform thin films over a large area by a flow-enabled self-assembly approach. The self-assembly of GO sheets was successfully performed by dragging the trapped solution of GO in confined geometry, which consisted of an upper stationary blade and a lower moving substrate on a motorized translational stage. The prepared GO thin films could be selectively reduced and facilitated from the simple laser direct writing process for programmable circuit printing with the desired configuration and less sample damage due to the non-contact mode operation without the use of photolithography, toxic chemistry, or high-temperature reduction methods. Furthermore, two different modes of the laser operating system for the reduction of GO films turned out to be valuable for the construction of novel graphene-based high-throughput electrical circuit boards compatible with integrating electronic module chips and flexible humidity sensors.