Deep learning-assisted 10-μL single droplet-based viscometry for human aqueous humor.

Probing the viscosity of human aqueous humor is crucial for optimizing micro-tube shunts in glaucoma treatment. However, conventional viscometers are not suitable for aqueous humor due to the limited sample volume-only tens of microliters-that can be safely extracted without causing permanent ocular damage. Here, we present an artificial intelligence-assisted microfluidic viscometry for measuring 10-μL aqueous humor collected at the point of care.

Multiscale rheology from bulk to nano using a quartz tuning fork-atomic force microscope.

Rheological characteristics exhibit significant variations at nanoscale confinement or near interfaces, compared to bulk rheological properties. To bridge the gap between nano- and bulk-scale rheology, allowing for a better and holistic understanding of rheology, developing a single experimental platform that provides rheological measurements across different scales, from nano to bulk, is desirable. Here, we present the novel methodology for multiscale rheology using a highly sensitive atomic force microscope based on a quartz tuning fork (QTF) force sensor.

Embryonic development through fertilization using high-quality bovine sperm separated in a biomimetic cervix environment.

This study is the first to identify bovine blastocysts through fertilization (IVF) of matured oocytes with a large quantity of high-quality sperm separated from a biomimetic cervix environment. We obtained high-quality sperm in large quantities using an IVF sperm sorting chip (SSC), which could mimic the viscous environment of the bovine cervix during ovulation and facilitates isolation of progressively motile sperm from semen. The viscous environment-on-a-chip was realized by formulating and implementing polyvinylpyrrolidone (PVP)-based solutions for the SSC medium.

Machine learning-enabled autonomous operation for atomic force microscopes.

The use of scientific instruments generally requires prior knowledge and skill on the part of operators, and thus, the obtained results often vary with different operators. The autonomous operation of instruments producing reproducible and reliable results with little or no operator-to-operator variation could be of considerable benefit. Here, we demonstrate the autonomous operation of an atomic force microscope using a machine learning-based object detection technique.

A simple and efficient cryopreservation method for mouse small intestinal and colon organoids for regenerative medicine.

Organoid cryopreservation method is one of key step in the organoid culture. We aimed to establish a simple and efficient cryopreservation method for mouse small intestinal organoids (MIOs) and colon organoids (MCOs) using various concentrations of cryoprotectant. Based on the theoretical simulation, we optimized the dimethyl sulfoxide (DMSO) concentration by pretreating the organoids with 5, 7.

Viscous Cervical Environment-on-a-Chip for Selecting High-Quality Sperm from Human Semen.

When ejaculated sperm travels through the vagina to the uterus, mucus secreted by the cervical canal generally filters out sperm having low motility and poor morphology. To investigate this selection principle in vivo, we developed a microfluidic sperm-sorting chip with a viscous medium (polyvinylpyrrolidone: PVP) to imitate the biophysical environment mimic system of the human cervical canal. The material property of the PVP solution was tuned to the range of viscosities of cervical mucus using micro-viscometry.

Quantitative Visualization of the Nanomechanical Young's Modulus of Soft Materials by Atomic Force Microscopy.

The accurate measurement of nanoscale mechanical characteristics is crucial in the emerging field of soft condensed matter for industrial applications. An atomic force microscope (AFM) can be used to conduct nanoscale evaluation of the Young's modulus on the target surface based on site-specific force spectroscopy. However, there is still a lack of well-organized study about the nanomechanical interpretation model dependence along with cantilever stiffness and radius of the tip apex for the Young's modulus measurement on the soft materials.

Probing the shear viscoelasticity of a nanoscale ionic liquid meniscus.

Ionic liquids (ILs) are emerging as novel solvents that exhibit peculiar mechanical properties in the form of thin films on metal surfaces under normal pressure. However, the mechanical properties of ILs in the form of nano-meniscus have not been analyzed yet. Here, we investigate the shear viscoelasticity of a single IL meniscus at the nanoscale.

Universal inherent fluctuations in statistical counting of large particles in slurry used for semiconductor manufacturing.

In the chemical mechanical polishing process of semiconductor manufacturing, the concentration of 'large' particles ([Formula: see text]0.5 μm) in the slurry, which is considerably larger in size than the main abrasives ([Formula: see text] 0.1 μm), is a critical parameter that strongly influences manufacturing defects, yields, and reliabilities of large-scale-integrated circuits.

True Random Number Generator (TRNG) Utilizing FM Radio Signals for Mobile and Embedded Devices in Multi-Access Edge Computing.

As transmissions of data between mobile and embedded devices in multi-access edge computing (MEC) increase, data must be protected, ensuring confidentiality and integrity. These issues are usually solved with cryptographic algorithms systems, which utilize a random number generator to create seeds and keys randomly. Their role in cryptography is so important that they need to be generated securely.

Theoretical study of buckling-based nonlinear transition near a static bifurcation point.

We theoretically investigate the nonlinear behavior of a buckled tip near the bifurcation point under external stress. We present a mechanical model for the buckled tip and derive the governing equation that describes the "buckling-to-flipping" nonlinear transition of the tip motion. Our minimal mechanistic model fully captures the velocity-dependent flipping phenomena, in which the flip position of the tip varies with the speed of the surface motion, as consistently observed in previous experiments.

Dynamic Responses of Electrically Driven Quartz Tuning Fork and qPlus Sensor: A Comprehensive Electromechanical Model for Quartz Tuning Fork.

A quartz tuning fork and its qPlus configuration show different characteristics in their dynamic features, including peak amplitude, resonance frequency, and quality factor. Here, we present an electromechanical model that comprehensively describes the dynamic responses of an electrically driven tuning fork and its qPlus configuration. Based on the model, we theoretically derive and experimentally validate how the peak amplitude, resonance frequency, quality factor, and normalized capacitance are changed when transforming a tuning fork to its qPlus configuration.

Buckling-Based Non-Linear Mechanical Sensor.

Mechanical sensors provide core keys for high-end research in quantitative understanding of fundamental phenomena and practical applications such as the force or pressure sensor, accelerometer and gyroscope. In particular, in situ sensitive and reliable detection is essential for measurements of the mechanical vibration and displacement forces in inertial sensors or seismometers. However, enhancing sensitivity, reducing response time and equipping sensors with a measurement capability of bidirectional mechanical perturbations remains challenging.

Isolation and characterization of a new Methanoculleus bourgensis strain KOR-2 from the rumen of Holstein steers.

Objective: To isolate and identify new methanogens from the rumen of Holstein steers in Korea.

Methods: Representative rumen contents were obtained from three ruminally cannulated Holstein steers (793±8 kg). Pre-reduced media were used for the growth and isolation of methanogens.

Bifurcation-enhanced ultrahigh sensitivity of a buckled cantilever.

Buckling, first introduced by Euler in 1744 [Euler L (1744) 24:231], a sudden mechanical sideways deflection of a structural member under compressive stress, represents a bifurcation in the solution to the equations of static equilibrium. Although it has been investigated in diverse research areas, such a common nonlinear phenomenon may be useful to devise a unique mechanical sensor that addresses the still-challenging features, such as the enhanced sensitivity and polarization-dependent detection capability. We demonstrate the bifurcation-enhanced sensitive measurement of mechanical vibrations using the nonlinear buckled cantilever tip in ambient conditions.

Liposarcoma of the spermatic cord in a Toy Poodle.

Liposarcoma of the spermatic cord is extremely rare in dogs and humans. This report describes the clinical signs, typical diagnostic imaging including ultrasound and computed tomography, and treatment of a liposarcoma of the spermatic cord of a Toy Poodle confirmed by histological examination after a surgical procedure. This case highlights the importance of preoperative diagnostic imaging and histopathological examination in dogs with an inguinal or scrotal mass.

Viscometry of single nanoliter-volume droplets using dynamic force spectroscopy.

The viscometry of minute amounts of liquid has been in high demand as a novel tool for medical diagnosis and biological assays. Various microrheological techniques have shown the capability to handle small volumes. However, as the liquid volume decreases down to nanoliter scale, increasingly dominant surface effects complicate the measurement and analysis, which remain a challenge in microrheology.

Probing nonlinear rheology layer-by-layer in interfacial hydration water.

Viscoelastic fluids exhibit rheological nonlinearity at a high shear rate. Although typical nonlinear effects, shear thinning and shear thickening, have been usually understood by variation of intrinsic quantities such as viscosity, one still requires a better understanding of the microscopic origins, currently under debate, especially on the shear-thickening mechanism. We present accurate measurements of shear stress in the bound hydration water layer using noncontact dynamic force microscopy.

Noncontact friction via capillary shear interaction at nanoscale.

Friction in an ambient condition involves highly nonlinear interactions of capillary force, induced by the capillary-condensed water nanobridges between contact or noncontact asperities of two sliding surfaces. Since the real contact area of sliding solids is much smaller than the apparent contact area, the nanobridges formed on the distant asperities can contribute significantly to the overall friction. Therefore, it is essential to understand how the water nanobridges mediate the 'noncontact' friction, which helps narrow the gap between our knowledge of friction on the microscopic and macroscopic scales.

Nanopipette combined with quartz tuning fork-atomic force microscope for force spectroscopy/microscopy and liquid delivery-based nanofabrication.

This paper introduces a nanopipette combined with a quartz tuning fork-atomic force microscope system (nanopipette/QTF-AFM), and describes experimental and theoretical investigations of the nanoscale materials used. The system offers several advantages over conventional cantilever-based AFM and QTF-AFM systems, including simple control of the quality factor based on the contact position of the QTF, easy variation of the effective tip diameter, electrical detection, on-demand delivery and patterning of various solutions, and in situ surface characterization after patterning. This tool enables nanoscale liquid delivery and nanofabrication processes without damaging the apex of the tip in various environments, and also offers force spectroscopy and microscopy capabilities.

Unified stress tensor of the hydration water layer.

We present the general stress tensor of the ubiquitous hydration water layer (HWL), based on the empirical hydration force, by combining the elasticity and hydrodynamics theories. The tapping and shear component of the tensor describe the elastic and damping properties of the HWL, respectively, in good agreement with experiments. In particular, a unified understanding of HWL dynamics provides the otherwise unavailable intrinsic parameters of the HWL, which offer additional but unexplored aspects to the supercooled liquidity of the confined HWL.

Synchronized reinjection and coalescence of droplets in microfluidics.

Coalescence of two kinds of pre-processed droplets is necessary to perform chemical and biological assays in droplet-based microfluidics. However, a robust technique to accomplish this does not exist. Here we present a microfluidic device to synchronize the reinjection of two different kinds of droplets and coalesce them, using hydrostatic pressure in conjunction with a conventional syringe pump.

Quartz tuning fork-based frequency modulation atomic force spectroscopy and microscopy with all digital phase-locked loop.

We present a platform for the quartz tuning fork (QTF)-based, frequency modulation atomic force microscopy (FM-AFM) system for quantitative study of the mechanical or topographical properties of nanoscale materials, such as the nano-sized water bridge formed between the quartz tip (~100 nm curvature) and the mica substrate. A thermally stable, all digital phase-locked loop is used to detect the small frequency shift of the QTF signal resulting from the nanomaterial-mediated interactions. The proposed and demonstrated novel FM-AFM technique provides high experimental sensitivity in the measurement of the viscoelastic forces associated with the confined nano-water meniscus, short response time, and insensitivity to amplitude noise, which are essential for precision dynamic force spectroscopy and microscopy.