Coupled surface plasmon–phonon polariton nanocavity arrays for enhanced mid-infrared absorption

Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micronthick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈0/150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10–12 microns) via excitation of coupled surface plasmon–phonon polaritons. The proposed metal–insulator–polar dielectric (gold–silicon–silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wav

An Ultrathin Conformable Vibration-Responsive Electronic Skin for Quantitative Vocal Recognition

Flexible and skin-attachable vibration sensors have been studied for use as wearable voice-recognition electronics. However, the development of vibration sensors to recognize the human voice accurately with a flat frequency response, a high sensitivity, and a flexible/conformable form factor has proved a major challenge. Here, we present an ultrathin, conformable, and vibration-responsive electronic skin that detects skin acceleration, which is highly and linearly correlated with voice pressure. This device consists of a crosslinked ultrathin polymer film and a hole-patterned diaphragm structure, and senses voices quantitatively with an outstanding sensitivity of 5.5 V Pa-1 over the voice frequency range. Moreover, this ultrathin device (<5 mu m) exhibits superior skin conformity, which enables exact voice recognition because it eliminates vibrational distortion on rough and curved skin surfaces. Our device is suitable for several promising voice-recognition applications, such as security authentication, remote control systems and vocal healthcare.11Ysciescopu

Prognostic significance of sealed-off perforation in colon cancer: a prospective cohort study

Background Perforated colon cancer is a rare complication, but has a high risk of recurrence. However, most studies have not distinguished sealed-off perforation from free perforation, and the prognosis is unclear. The aim of this study was to evaluate the oncologic outcome of colon cancer with sealed-off perforation. Methods Eighty-six consecutive patients who underwent resection for colon cancer with sealed-off or free perforation were included. We defined sealed-off perforation as a colon perforation with localized abscess identified on operative, computed tomography, or pathologic findings, with no evidence of free perforation, including fecal contamination and dirty fluid collection in the peritoneal cavity. Oncologic outcomes were compared between patients with colon cancer with sealed-off perforation and free perforation using a log-rank test and Cox regression analysis. Results The sealed-off perforation group included 62 patients, and 24 patients were in the free perforation group. TNM stage and lymphatic, venous, and perineural invasion were similar between the groups. The median follow-up period was 28.9 months (range 0–159). The sealed-off perforation group had better prognosis compared with the free perforation group in terms of progression-free survival (PFS) and overall survival (OS), although there were no statistically significant differences in PFS (5-year PFS 53.7% vs. 40.5%, p = 0.148; 5-year OS 53.6% vs. 22.9%, p = 0.001). However, in multivariable analysis using the Cox progression test, sealed-off perforation did not show a significant effect on cancer progression (p = 0.138) and OS (p = 0.727). Conclusions Colon cancer with sealed-off perforation showed no difference in prognosis compared with free perforation.Not applicable

The acidic tumor microenvironment enhances PD-L1 expression via activation of STAT3 in MDA-MB-231 breast cancer cells

Abstract Tumor acidosis, a common phenomenon in solid cancers such as breast cancer, is caused by the abnormal metabolism of cancer cells. The low pH affects cells surrounding the cancer, and tumor acidosis has been shown to inhibit the activity of immune cells. Despite many previous studies, the immune surveillance mechanisms are not fully understood. We found that the expression of PD-L1 was significantly increased under conditions of extracellular acidosis in MDA-MB-231 cells. We also confirmed that the increased expression of PD-L1 mediated by extracellular acidosis was decreased when the pH was raised to the normal range. Gene set enrichment analysis (GSEA) of public breast cancer patient databases showed that PD-L1 expression was also highly correlated with IL-6/JAK/STAT3 signaling. Surprisingly, the expression of both phospho-tyrosine STAT3 and PD-L1 was significantly increased under conditions of extracellular acidosis, and inhibition of STAT3 did not increase the expression of PD-L1 even under acidic conditions in MDA-MB-231 cells. Based on these results, we suggest that the expression of PD-L1 is increased by tumor acidosis via activation of STAT3 in MDA-MB-231 cells.This work was supported by grants from the National Research Foundation of Korea (NRF) funded by the Korean government (NRF-2018R1A5A2025964) and the Seoul National University Hospital (SNUH) Research Fund (04–20200230). This study was also carried out with support from the R&D Program for Forest Science Technology (Project No. 2020195A00–2122-BA01) of the Korea Forest Service (Korea Forestry Promotion Institute) and Cooperative Research Program for the Agriculture Science and Technology Development (Project No. PJ01589402 and No. PJ016202022) Rural Development Administration, Republic of Korea

Dispersion and polarization engineering in silicon and plasmonic nanophotonic structures

Plasmonics and silicon photonics are the two main branches of nanophotonics that have been advanced over the last decade. Plasmonics use metallic nanostructures to confine the light down to the subwavelength scale and to enhance the field intensity for a strong light-matter interaction; however, the main drawback is a high metallic loss and a lack in large-scale fabrication technique. Meanwhile, silicon or on-chip photonics use a low-loss dielectric to guide and manipulate the light in micro/nanoscale chips, and can take advantage of the current CMOS manufacturing system; yet, further scaling down is limited by the diffraction limit. In this thesis, three sets of nanophotonic devices — silicon, plasmonic, and hybrid — are presented to address the aforementioned issues. First, a large-area patterning of metal nanostructures is examined with a resistless nanoimprinting. This approach provides a simple, reproducible, and accurate means to fabricate metallic nanopatterns, and the demonstrated plasmonic nanocavities effectively absorb the light. The reflection phase-shift at the metal-dielectric interface is also studied, and an omnidirectional bandpass filter is designed. Second, I propose using a silicon/plasmonic hybrid nanostructure to balance the advantages of plasmonics and Si photonics; the subwavelength feature from plasmonics; and the low-loss propagation and CMOS compatibility from Si photonics. Three examples of polarization-managed hybrid devices are presented, with ultra-compact device sizes. Finally, a waveguide modal dispersion engineering is explored with mode-coupling. Broadband second-harmonic phase-matchings are achieved, and degenerate-optical-parametric-amplifications and second-harmonic-generations are examined

Copper nanorod array assisted silicon waveguide polarization beam splitter

We present the design of a three-dimensional (3D) polarization beam splitter (PBS) with a copper nanorod array placed between two silicon waveguides. The localized surface plasmon resonance (LSPR) of a metal nanorod array selectively cross-couples transverse electric (TE) mode to the coupler waveguide, while transverse magnetic (TM) mode passes through the original input waveguide without coupling. An ultra-compact and broadband PBS compared to all-dielectric devices is achieved with the LSPR. The output ports of waveguides are designed to support either TM or TE mode only to enhance the extinction ratios. Compared to silver, copper is fully compatible with complementary metal-oxide-semiconductor (CMOS) technology. (C) 2014 Optical Society of Americ