Biomedical Engineering

Optical and confocal microscopy are used to image biological samples, including a sectioned piece of mouse brain. These methods help scientists compare how sample type, resolution, and depth of focus affect image quality. They are especially useful in biology labs that study larger biological structures.

Optical microscopes have been used for centuries, and modern tools such as confocal imaging and digital image processing have expanded what they can do. Even so, the best optical microscopes...

Scanning electron microscopy (SEM) is used to image biological samples after careful preparation. SEM uses an electron beam in a vacuum to nondestructively view conductive materials and surface features. It works like an optical microscope, but it gives much higher magnification and resolution.

The difference comes from the beam used to form the image. Optical microscopes are limited by the diffraction of visible light, which has a wavelength of about 500 nm. SEM uses an energized electron...

Metal and magnetic nanoparticles are used in targeted drug delivery and controlled drug release. In biomedical research, these particles are often compared with polymeric and liposomal carriers because those materials are biocompatible. Current work also focuses on metallic and magnetic nanoparticles, which can be useful for drug and gene delivery and for therapy.

Gold, silver, and paramagnetic nanoparticles are common examples in this field. These materials were first used as contrast agents...

High-frequency ultrasound imaging can show the shape and blood flow of small pulsatile arteries and veins. The system used here provides high-resolution images of vessels in mice and rats. It is a practical way to study vessel morphology and hemodynamics, which means vessel structure and blood movement.

Ultrasound is a relatively inexpensive, portable, and versatile method for noninvasive vessel assessment. It can be used in humans as well as in large and small animals. Compared with computed...

3D strain analysis of aortic vessel motion helps show how an abdominal aortic aneurysm deforms over time. Strain is a measure of relative deformation, and it can be used to describe how soft tissue changes shape under load. Blood vessels, skin, tendons, and other organs are made of elastin and collagen, which give them elasticity and strength.

The arrangement of these fibers depends on the soft tissue type. Some tissues have one main fiber direction, while others form more complex mesh-like...

Photoacoustic tomography (PAT) is a biomedical imaging method that uses light-generated sound waves to study tissue composition. It can detect blood and lipid components in the infrarenal aorta, the lower part of the aorta below the kidneys. This makes PAT useful for cardiovascular research and tumor imaging.

PAT addresses several limits of current imaging methods. Many existing techniques can take a long time, cost a lot, use harmful contrast agents, or require more invasive procedures. Some...

Gated MRI of mouse heart motion uses high-field, small-bore magnetic resonance imaging with physiological monitoring. It records cine loops, which are moving image sequences, of the murine cardiovascular system. This approach helps assess left-ventricular function, show vascular networks, and measure organ motion caused by breathing.

Several small animal imaging methods can be used for the same type of study. High-frequency ultrasound offers high spatial and temporal resolution, but imaging...

Computational fluid dynamics, or CFD, can model blood flow from patient- or animal-specific vessels. In this approach, subject-based vessel segmentations are built first. Then open-source and commercial tools are combined to create a high-resolution numerical solution inside a flow model.

These simulations help researchers study hemodynamics, which is the way blood moves through vessels. Hemodynamic conditions are linked to the development and progression of atherosclerosis, aneurysms, and...

Near-infrared fluorescence imaging uses fluorescent probes to visualize biomolecular structures inside tissues. It is a useful optical method for studying disease in living systems. The technique can show specific targets without the limits of some conventional imaging methods.

Compared with single photon emission computed tomography (SPECT) and positron emission tomography (PET), near-infrared fluorescence imaging is rapid and high-throughput. It also does not use ionizing radiation. These...

Portable blood pressure monitoring uses cuff-based methods to measure systolic and diastolic pressure in humans and rodents. These approaches rely on the same basic hemodynamic principles, or how blood moves and creates pressure in vessels. The page focuses on how current cuff technology works and why it is useful in both clinical and research settings.

For humans, commercially available cuffs can connect to mobile devices and are usually small and easy to carry. That makes it possible to take...

An ECG signal records the heart's electrical activity from electrodes placed on the body. It shows heart rhythm and can help reveal cardiac problems such as poor blood flow to the heart and structural abnormalities.

The signal comes from action potentials created by contractions of the heart wall. These electrical currents spread through the body and create different electrical potentials at different points on the skin. Electrodes, which are biological transducers made of metals and salts,...

Resorbable sutures are tested for strength as they break down in different pH conditions. These sutures are designed to hold a wound closed long enough for healing and then gradually disintegrate in the body. The study compares how that strength changes after exposure to neutral, acidic, and alkaline solutions, which represent pH environments found in the human body.

Sutures have been used for more than 4000 years as a medical tool. Early records describe linen as an early biomaterial, and...

X-ray imaging can show the inside of an object without cutting it open. In this high school science topic, micro-CT uses many 2D X-ray projections to build a 3D view of a sample. The result is similar to a medical X-ray, but it gives depth information instead of just a flat image.

X-rays have played an important role in science for a long time. Their discovery and accidental use led to the first Nobel Prize in Physics. The famous 1895 image of Dr. Röntgen’s wife’s hand shows the same basic...

ACL injury in the knee can lead to post-traumatic osteoarthritis, or PTOA, which is joint damage that develops after an injury. About one-third of people show signs of PTOA on X-rays within the first decade after ACL injury. Although ACL reconstruction restores knee stability, it and current rehabilitation methods do not prevent PTOA.

Rat models are widely used to study how ACL injury leads to PTOA. The most common method is ACL transection, where the ligament is cut to destabilize the joint.

SPECT/CT imaging combines nuclear imaging and X-ray imaging to study mice. It uses a radionuclide, which is a radioactive tracer, that is injected into the animal. After the tracer spreads through the body, the mouse is scanned and the images are reconstructed into a 3D dataset.

This method can show anatomy, physiology, and metabolism in one experiment. That makes it useful for improving disease diagnosis and for tracking how a disease changes over time. Because it provides both functional and...