The nanostructures and patterns that exist in nature have inspired researchers to develop revolutionary components for use in modern technologies and our daily lives. The nanoscale imaging of biological samples with sophisticated analytical tools, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), has afforded a precise understanding of structures and has helped reveal the mechanisms contributing to the behaviors of the samples but has done so with the loss of photonic properties. Here, we present a new method for printing biocompatible “superlenses” directly on biological objects to observe subdiffraction-limited features under an optical microscope in color. We demonstrate the nanoscale imaging of butterfly wing scales with a super-resolution and larger field-of-view (FOV) than those of previous dielectric microsphere techniques. Our approach creates a fast and flexible path for the direct color observation of nanoscale biological features in the visible range and enables potential optical measurements at the subdiffraction-limited scale.

Conventional MEMS actuators are not suitable for underwater applications such as cell grasping due to two main reasons: 1) their required actuation voltage are typically higher than 2 V, which would cause electrolysis in water and 2) they have small displacement/deflection due to their inherent driving principles. In this paper, three-different types of novel polymer-based MEMS underwater actuators developed in our laboratory are discussed: 1) ionic conducting polymer films (ICPF) actuator, which actuates by stress gradient induced by ionic movement due to electric field; 2) parylene thermal actuator, which actuates due to the induced stress gradient across a structure made of different layers of materials with different thermal expansion coefficients; and 3) polyaniline (PANI) actuator, which actuates due to its volumetric change caused by a reversible electrochemical oxidation-reduction (redox) reaction. All these polymer micro actuators can be actuated underwater with large deflections and require less power input than conventional MEMS actuators. The experimental results from characterizing these prototype actuators are presented in this paper.

SUMO (small ubiquitin-related modifier)-specific proteases catalyse the maturation and de-conjugation processes of the sumoylation pathway and modulate various cellular responses including nuclear metabolism and cell cycle progression. The active-site cysteine residue is conserved among all known SUMO-specific proteases and is not substitutable by serine in the hydrolysis reactions demonstrated previously in yeast. We report here that the catalytic domain of human protease SENP1 (SUMO-specific protease 1) mutant SENP1CC603S carrying a mutation of cysteine to serine at the active site is inactive in maturation and de-conjugation reactions. To further understand the hydrolytic mechanism catalysed by SENP1, we have determined, at 2.8 Å resolution (1 Å=0.1 nm), the X-ray structure of SENP1CC603S–SUMO-1 complex. A comparison of the structure of SENP2–SUMO-1 suggests strongly that SUMO-specific proteases require a self-conformational change prior to cleavage of peptide or isopeptide bond in the maturation and de-conjugation processes respectively. Moreover, analysis of the interface of SENP1 and SUMO-1 has led to the identification of four unique amino acids in SENP1 that facilitate the binding of SUMO-1. By means of an in vitro assay, we further demonstrate a novel function of SENP1 in hydrolysing the thioester linkage in E1-SUMO and E2-SUMO complexes. The results disclose a new mechanism of regulation of the sumoylation pathway by the SUMO-specific proteases.

This paper describes the design, microfabrication, and testing of a novel polycrystalline-diamond (poly-C)-based microprobe for possible applications in neural prosthesis. The probe utilizes undoped poly-C with a resistivity on the order of 10⁵ Omega middot cm as a supporting material, which has a Young's modulus in the range of 400-1000 GPa and is biocompatible. Boron-doped poly-C with a resistivity on the order of 10^-3 Omega middot cm is used as an electrode material, which provides a chemically stable surface for both chemical and electrical detections in neural studies. The probe has eight poly-C electrode sites with diameters ranging from 2 to 150 mum; the electrode capacitance is approximately 87 muF/cm². The measured water potential window of the poly-C electrode spans across negative and positive electrode potentials and typically has a total value of 2.2 V in 1 M KCl. The smallest detectable concentration of norepinephrine (a neurotransmitter) was on the order of 10 nM. The poly-C probe has also been successfully implanted in the auditory cortex area of a guinea pig brain for in vivo neural studies. The recorded signal amplitude was 30-40 muV and had a duration of 1 ms.

Wearing masks has been a recommended protective measure due to the risks of coronavirus disease 2019 (COVID‐19) even in its coming endemic phase. Therefore, deploying a “smart mask” to monitor human physiological signals is highly beneficial for personal and public health. This work presents a smart mask integrating an ultrathin nanocomposite sponge structure‐based soundwave sensor (≈400 µm), which allows the high sensitivity in a wide‐bandwidth dynamic pressure range, i.e., capable of detecting various respiratory sounds of breathing, speaking, and coughing. Thirty‐one subjects test the smart mask in recording their respiratory activities. Machine/deep learning methods, i.e., support vector machine and convolutional neural networks, are used to recognize these activities, which show average macro‐recalls of ≈95% in both individual and generalized models. With rich high‐frequency (≈4000 Hz) information recorded, the two‐/tri‐phase coughs can be mapped while speaking words can be identified, demonstrating that the smart mask can be applicable as a daily wearable Internet of Things (IoT) device for respiratory disease identification, voice interaction tool, etc. in the future. This work bridges the technological gap between ultra‐lightweight but high‐frequency response sensor material fabrication, signal transduction and processing, and machining/deep learning to demonstrate a wearable device for potential applications in continual health monitoring in daily life.

Light detection and ranging (LiDAR) using various operational principles has been applied in many fields, e.g., robotics navigation, autonomous vehicles, unmanned aerial flyers, land surveying, etc. The multichannel LiDAR system is of great importance in the field of autonomous driving due to its larger field of view (FoV). However, the number of transceivers limits the vertical angular resolution of multichannel LiDAR systems and makes them costly. On the other hand, the emergence of microelectromechanical systems (MEMS) mirrors may provide a highly promising solution to a low-cost, high angular resolution LiDAR system. We have demonstrated a MEMS mirror-based 360° LiDAR system with high angular resolution and will present the detailed design process and obtained experimental results in this paper. With the combination of the MEMS mirror and a rotation platform for the LiDAR system, a 360° × 8.6° (horizontal × vertical) FoV was achieved. Compared with existing commercial multichannel 360° LiDAR systems, our system has 13.8 times better angular resolution than the Velodyne HDL-64 LiDAR sensor. The experimental results verified an excellent performance of 0.07° × 0.027° (horizontal × vertical) angular resolution, which enhances the panoramic scanning and imaging capability of the LiDAR system, potentially providing more accurate 3D scanning applications in areas such as autonomous vehicles, indoor surveying, indoor robotics navigation, etc.