A Miniaturized, Fuel-Free, Self-Propelled, Bio-Inspired Soft Actuator for Copper Ion Removal.

We present a novel miniaturized, gear-shaped, fuel-free actuator capable of autonomously propelling itself in an aquatic environment to absorb heavy metals, such as copper ions. While hydrogel-based absorbents are promising solutions for cationic pollutant remediation, their stationary nature limits their effectiveness in areas where contaminants are unevenly distributed. To address this, we developed a bio-inspired soft actuator that mimics natural propulsion mechanisms.

Design and Fabrication of Micro Saw Enabling Root-Side Cutting of Bone.

A novel micro saw was fabricated using a combination of photolithography and electroplating techniques, resembling a miniature timing belt with sideways blades. The rotation or oscillation direction of the micro saw is designed to be perpendicular to the cutting direction so that transverse cutting of the bone is attainable to extract a preoperatively planned bone-cartilage donor for osteochondral auto-graft transplantation. The mechanical property of the fabricated micro saw obtained using the nanoindentation test shows that the mechanical properties of the micro saw are almost an order of magnitude higher than bone, which indicates its potential bone-cutting application.

Self-Assembled 1-Octadecanethiol Membrane on Pd/ZnO for a Selective Room Temperature Flexible Hydrogen Sensor.

A layer of self-assembled 1-octadecanethiol was used to fabricate a palladium (Pd)/zinc oxide (ZnO) nanoparticle-based flexible hydrogen sensor with enhanced response and high selectivity at room temperature. A palladium film was first deposited using DC sputtering technique and later annealed to form palladium nanoparticles. The formation of uniform, surfactant-free palladium nanoparticles contributed to improved sensor response towards hydrogen gas at room temperature.

Development of a novel self-sanitizing mask prototype to combat the spread of infectious disease and reduce unnecessary waste.

With the spread of COVID-19, significant emphasis has been placed on mitigation techniques such as mask wearing to slow infectious disease transmission. Widespread use of face coverings has revealed challenges such as mask contamination and waste, presenting an opportunity to improve the current technologies. In response, we have developed the Auto-sanitizing Retractable Mask Optimized for Reusability (ARMOR).

A novel print-and-release method to prepare microplastics using an office-grade laserjet printer; a low-cost solution for preliminary studies.

Microscopic plastic particles (microplastics) are widespread anthropogenic contaminants that are impacting aquatic ecosystems. Among the five most prevalent types of microplastics (polystyrene, polyamide, polyvinyl chloride, polyethylene, and polypropylene) in aquatic environments, the impact of polystyrene, polyethylene, and polypropylene has drawn more attention due to their high transportability. A lack of reliable inexpensive methods to accurately replicate the realistic microplastic samples extracted from environmental matrixes with the desired size and geometry is one of the main challenges in the design of experiments for systematic studies.

A Carbon Nanotube-Metal Oxide Hybrid Material for Visible-Blind Flexible UV-Sensor.

Flexible sensors with low fabrication cost, high sensitivity, and good stability are essential for the development of smart devices for wearable electronics, soft robotics, and electronic skins. Herein, we report a nanocomposite material based on carbon nanotube and metal oxide semiconductor for ultraviolet (UV) sensing applications, and its sensing behavior. The sensors were prepared by a screen-printing process under a low-temperature curing condition.

A Novel Bismuth-Chitosan Nanocomposite Sensor for Simultaneous Detection of Pb(II), Cd(II) and Zn(II) in Wastewater.

A novel bismuth (Bi)-biopolymer (chitosan) nanocomposite screen-printed carbon electrode was developed using a Bi and chitosan co-electrodepositing technique for detecting multiple heavy metal ions. The developed sensor was fabricated with environmentally benign materials and processes. In real wastewater, heavy metal detection was evaluated by the developed sensor using square wave anodic stripping voltammetry (SWASV).

Continuous Positive Airway Pressure Therapy Restores Cardiac Mechanical Function in Patients With Severe Obstructive Sleep Apnea: A Randomized, Sham-Controlled Study.

Background: Continuous positive airway pressure (CPAP) therapy might decrease left ventricular (LV) and right ventricular (RV) loads and improve cardiac mechanical function in patients with obstructive sleep apnea (OSA). However, the benefits of CPAP therapy for cardiac mechanical function in patients with OSA have not previously been proved in a randomized, sham-controlled clinical trial. This study therefore investigated the effects of CPAP therapy on LV and RV mechanical function in patients with severe OSA and compared them with the effects of a sham intervention.

A Rapid Electrochemical Surface Modification Process for Nanotextured Gold Electrodes.

Due to its unique physical and chemical properties, gold has been widely applied as electrode material for various applications. In recent years, with the increasing requirement on the electrode performance, researchers attempted to involve nanostructures into the electrode through various routes, which demonstrated the performance improvement but still are limited by the process complexity, toxic agents and high cost. In this work, a simple and fast electrochemical surface modification process of gold electrodes was developed.

Microfluidic Devices Developed for and Inspired by Thermotaxis and Chemotaxis.

Taxis has been reported in many cells and microorganisms, due to their tendency to migrate toward favorable physical situations and avoid damage and death. Thermotaxis and chemotaxis are two of the major types of taxis that naturally occur on a daily basis. Understanding the details of the thermo- and chemotactic behavioral response of cells and microorganisms is necessary to reveal the body function, diagnosing diseases and developing therapeutic treatments.

Picomolar Detection of Hydrogen Peroxide using Enzyme-free Inorganic Nanoparticle-based Sensor.

A philosophical shift has occurred in the field of biomedical sciences from treatment of late-stage disease symptoms to early detection and prevention. Ceria nanoparticles (CNPs) have been demonstrated to neutralize free radical chemical species associated with many life-threatening disease states such as cancers and neurodegenerative diseases by undergoing redox changes (Ce  ↔ Ce). Herein, we investigate the electrochemical response of multi-valent CNPs in presence of hydrogen peroxide and demonstrate an enzyme-free CNP-based biosensor capable of ultra-low (limit of quantitation: 0.

A Graphene-Based Nanosensor for In Situ Monitoring of Polycyclic Aromatic Hydrocarbons (PAHs).

A graphene-based nanosensor was developed for in situ monitoring of polycyclic aromatic hydrocarbons (PAHs) in aqueous solutions. The sensor was fabricated using photolithography and etching of Au/Ti film on a silicon wafer followed by the transfer of a single graphene layer which was prepared separately by chemical vapor deposition (CVD). The performance of the graphene nanosensor was characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).

Thermocapillarity in Microfluidics-A Review.

This paper reviews the past and recent studies on thermocapillarity in relation to microfluidics. The role of thermocapillarity as the change of surface tension due to temperature gradient in developing Marangoni flow in liquid films and conclusively bubble and drop actuation is discussed. The thermocapillary-driven mass transfer (the so-called Benard-Marangoni effect) can be observed in liquid films, reservoirs, bubbles and droplets that are subject to the temperature gradient.

Inhibitory effect of Korean Red Ginseng on melanocyte proliferation and its possible implication in GM-CSF mediated signaling.

Korean Red Ginseng (KRG) has been reported to exert anticancer, anti-oxidant, and anti-inflammatory effects. However, there has been no report on the effect of KRG on skin pigmentation. In this study, we investigated the inhibitory effect of KRG on melanocyte proliferation.

Graphene-P(VDF-TrFE) multilayer film for flexible applications.

A flexible, transparent acoustic actuator and nanogenerator based on graphene/P(VDF-TrFE)/graphene multilayer film is demonstrated. P(VDF-TrFE) is used as an effective doping layer for graphene and contributes significantly to decreasing the sheet resistance of graphene to 188 ohm/sq. The potentiality of graphene/P(VDF-TrFE)/graphene multilayer film is realized in fabricating transparent, flexible acoustic devices and nanogenerators to represent its functionality.

Laser irradiated nano-architectured undoped tin oxide arrays: mechanism of ultrasensitive room temperature hydrogen sensing.

Undoped nanostructured tin oxide (SnO(2)) arrays were prepared on oxidized Si substrates by nanosecond pulsed laser interference irradiation for hydrogen gas sensing applications. Scanning electron microscopy (SEM), in combination with Atomic Force Microscopy (AFM), showed that the SnO(2) surface consisted of periodic features of ∼130 nm width, ∼228 nm spacing, an average height of ∼8 nm along the periodicity and tens of microns length. The SnO(2) nanostructured arrays and precursor thin films were tested by cyclic exposure under dynamic conditions of hydrogen in the concentration range of 300-9000 ppm.

Surface modification of carbon post arrays by atomic layer deposition of ZnO film.

The applicability of atomic layer deposition (ALD) process to the carbon microelectromechanical system technology was studied for a surface modification method of the carbon post electrodes. A conformal coating of the ALD-ZnO film was successfully demonstrated on the carbon post arrays which were fabricated by the traditional photolithography and subsequent two-step pyrolysis. A significant Zn diffusion into the underlying carbon posts was observed during the ALD process.

A micropump controlled by EWOD: wetting line energy and velocity effects.

A Laplace pressure gradient between a droplet and a liquid meniscus was utilized to create an on-demand constant flow rate capillary pump. Electrowetting on dielectric was implemented to induce the pressure gradient in the microchannel. For an initial droplet volume of 0.

Wettability control and flow regulation using a nanostructure-embedded surface.

This work addresses the synthesis, integration and characterization of a nanostructure-embedded thermoresponsive surface for flow regulation. In order to create a hierarchic structure which consists of microscale texture and nanoscale sub-texture, hybrid multilayers consisting of poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA) and colloidal silica nanoparticles (average diameter = 22 nm and 7 nm) were used. Based on the electrostatic interactions between the polyelectrolytes and nanoparticles, a layer-by-layer deposition technique in combination with photolithography was employed to obtain a localized, conformally-coated patch in a microchannel.

Graphene-based bimorph microactuators.

A novel graphene-on-organic film fabrication method that is compatible with a batch microfabrication process was developed and used for electromechanically driven microactuators. A very thin layer of graphene sheets was monolithically integrated and the unique material characteristics of graphene including negative thermal expansion and high electrical conductivity were exploited to produce a bimorph actuation. A large displacement with rapid response was observed while maintaining the low power consumption.

Impact of drops on the surface of immiscible liquids.

Impact of drops on the surface of an immiscible liquid is studied. We show that in addition to the commonly-observed lens structure at the air-liquid interface, drops released from critical heights above the target liquid can sustain the impact and at the end maintain a spherical ball-shape configuration above the surface despite undergoing large deformation. The existence of this metastable state of the drop above the free surface and its transition into the more stable submerged lens configuration at the air-liquid interface is investigated.

Organic electrochemical transistor based immunosensor for prostate specific antigen (PSA) detection using gold nanoparticles for signal amplification.

We demonstrated a highly sensitive organic electrochemical transistor (OECT) based immunosensor with a low detection limit for prostate specific antigen/alpha1-antichymotrypsin (PSA-ACT) complex. The poly(styrenesulfonate) doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) based OECT with secondary antibody conjugated gold nanoparticles (AuNPs) provided a detection limit of the PSA-ACT complex as low as 1pg/ml, as well as improved sensitivity and a dynamic range, due to the role of AuNPs in the signal amplification. The sensor performances were particularly improved in the lower concentration range where the detection is clinically important for the preoperative diagnosis and screening of prostate cancer.

On-chip surface plasmon resonance sensor.

A novel on-chip micro SPR (surface plasmon resonance) sensor based on an optoelectronic platform has been developed. This research aims for a fully integrated SPR sensor system to achieve a miniaturized, high throughput sensor system. A novel method for design and fabrication of the solid state SPR sensor device has been investigated.

Effect of air-pressure on room temperature hydrogen sensing characteristics of nanocrystalline doped tin oxide MEMS-based sensor.

Nanocrystalline indium oxide (In2O3)-doped tin oxide (SnO2) thin film sensor has been sol-gel dip-coated on a microelectrochemical system (MEMS) device using a sol-gel dip-coating technique. Hydrogen (H2) at ppm-level has been successfully detected at room temperature using the present MEMS-based sensor. The room temperature H2 sensing characteristics (sensitivity, response and recovery time, and recovery rate) of the present MEMS-based sensor has been investigated as a function of air-pressure (50-600 Torr) with and without the ultraviolet (UV) radiation exposure.

Autostereoscopic three-dimensional display based on a micromirror array.

A novel approach for three-dimensional (3-D) display systems implemented with a micromirror array was proposed, designed, realized, and tested. The major advantages of this approach include the following: (1) micromirrors are reflective and hence achromatic (panchromatic), (2) a wide variety of displays can be used as image sources, and (3) time multiplexing can be introduced on top of space multiplexing to optimize the viewing zone arrangements. A two-view (left and right) 3-D autostereoscopic display system was first constructed.