Reconfigurable and Broadband Polarimetric Photodetector

The sensitive detection of light polarization besides the intensity and wavelength, can provide a new degree of freedom for more and clearer information of imaging targets in night, fog, and smoke environment. However, the conventional filter-integrated polarimetric photodetectors suffer from the complicated fabrication process and limited spectral range. Herein, broadband and polarization-sensitive photodetectors are achieved with reconfigurable operation mode, utilizing the linear dichroism and narrow band gap of 2D As_0.4P_0.6 with in-plane anisotropic structure. In As_0.4P_0.6-MoTe₂ heterojunction device, both photo-gating and photovoltaic modes are operated and switchable, contributing to high responsivity (1590 A W⁻¹ at 405 nm and 14.7 A W⁻¹ at 1550 nm) and ultrafast speed (25 µs) in the wide spectral band (405–1550 nm). Interestingly, an optical reversal is observed on both linear dichroism and polarimetric photocurrent due to the wavelength-dependent polarization reverse nature of the As_0.4P_0.6 flakes. The dichroism ratio of photocurrent can be modulated from unity to ≈10 by varying the gate voltage, enabling the reconfigurable detection mode from polarization-independence to polarization-susceptibility. This study demonstrates a new prototype device comprising low symmetric van der Waals heterostructure, possessing the gate-tunability on both photo-gain and dichroism ratio, toward high performance, reconfigurable, broadband, and polarization-resolved photodetection and imaging applications.     

Tailoring the Surface Chemistry of PEDOT:PSS to Promote Supported Lipid Bilayer Formation

This communication reports on a versatile and substrate-agnostic method to tune the surface chemistry of conducting polymers with the aim of bridging the chemical mismatch between bioelectronic devices and biological systems. As a proof of concept, the surface of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is grafted with a short-chain oligoethylene glycol monolayer to favor the formation of cell-derived supported lipid bilayers (SLBs). This method is tuned to optimize the affinity between the supported lipid bilayer and the conducting polymer, leading to significant improvements in bilayer quality and therefore electronic readouts. To validate the impact of surface functionalization on the system's ability to transduce biological phenomena into quantifiable electronic signals, the activity of a virus commonly used as a surrogate for SARS-CoV-2 (mouse hepatitis virus) is monitored with and without surface treatment. The functionalized devices exhibit significant improvements in electronic output, stemming from the improved SLB quality, therefore strengthening the case for the use of such an approach in membrane-on-a-chip systems.     

Cleanroom-Free Fabrication of Microneedles for Multimodal Drug Delivery

Microneedles have recently emerged as a powerful tool for minimally invasive drug delivery and body fluid sampling. To date, high-resolution fabrication of microneedle arrays (MNAs) is mostly achieved by the utilization of sophisticated facilities and expertise. Particularly, hollow microneedles have usually been manufactured in cleanrooms out of silicon, resin, or metallic materials. Such strategies do not support the fabrication of microneedles from biocompatible/biodegradable materials and limit the capability of multimodal drug delivery for the controlled release of different therapeutics through a combination of injection and sustained diffusion. This study implements low-cost 3D printers to fabricate relatively large needle arrays, followed by repeatable shrink-molding of hydrogels to form high-resolution molds for solid and hollow MNAs with controllable sizes. The developed strategy further enables modulating surface topography of MNAs to tailor their surface area and instantaneous wettability for controllable drug delivery and body fluid sampling. Hybrid gelatin methacryloyl (GelMA)/polyethylene glycol diacrylate (PEGDA) MNAs are fabricated using the developed strategy that can easily penetrate the skin and enable multimodal drug delivery. The proposed method holds promise for affordable, controllable, and scalable fabrication of MNAs by researchers and clinicians for controlled spatiotemporal administration of therapeutics and sample collection.     

Corrosion and Erosion Analysis of AlCrN/CrN Multilayered Coating Applied by Cathodic Arc Physical Vapor Deposition (PVD)

Protection of Metals and Physical Chemistry of Surfaces - A multilayered AlCrN/CrN coating was applied on stainless steel C-450 precipitation hardened stainless steel by cathodic arc vapor...     

Autonomous 3D vision-based bolt loosening assessment using micro aerial vehicles

Earlier identification of bolt loosening is crucial to maintain structural integrity and prevent system-level collapse. In this study, a novel drone-based 3D vision methodology has been proposed for autonomous bolt loosening assessment. First, a low-cost micro aerial vehicle with various types of sensors is designed. Second, a drone-based autonomous image collection method is proposed. Third, a 3D point cloud of the bolted connection is generated using the acquired images. Fourth, 3D point cloud processing methods are proposed to localize and quantify bolt loosening. The proposed method has been implemented on structural beam–column connections. The results show that the proposed drone-based data collection method can effectively acquire images for 3D reconstruction. The 3D point cloud processing methods can reliably localize and quantify bolt loosening at high accuracy. The proposed method provides a more robust and comprehensive evaluation of bolt loosening, compared to existing 2D vision methods, which process 2D images captured at a specific camera view.