Optical Cardiovascular Imaging
Robert J. Gropler, David K. Glover, Albert J. Sinusas, Heinrich Taegtmeyer in Cardiovascular Molecular Imaging, 2007
Any optical imaging system must consist of a two-dimensional optical sensor and a stable light source, such as a laser or DC-powered tungsten-halogen lamp, mercury source, or light emitting diodes. Figure 2 describes a typical design. It consists of a 16 × 16 PDA, 256-channel signal conditioner/amplifier, analog-to-digital converter, and a computer. Excitation light passes through a 520 ± 45 nm filter, is reflected by a 585 nm dichroic mirror, passes through a 50 mm 1.2f lens and illuminates the preparation in the tissue chamber. The fluorescence emitted from the preparation is collected by the same lens, passes through the dichroic mirror, a 610 nm long-pass filter, and is collected by the 16 × 16 PDA. The signal from the PDA is then amplified, digitized, and stored on the computer.
Eukaryotic Mechanosensitive Ion Channels
Tian-Le Xu, Long-Jun Wu in Nonclassical Ion Channels in the Nervous System, 2021
Interestingly, Piezo1 and Piezo2 have distinct channel properties [3,22]. First, while both of them show voltage-dependent inactivation, the time constant for inactivation kinetics (τinac) of Piezo2 (<10 ms) in heterologous systems is relatively faster than that of Piezo1 (>15 ms) [22]. Secondly, Piezo1 can be effectively activated by stretch with a P50 of ~ −30 mmHg, while Piezo2 responds poorly to stretch stimulation [24]. Third, physiological forces, like blood flow-induced shear stress, can initiate a Ca2+ response by Piezo1 [30], while similar responses by Piezo2 have not yet been reported. Fourth, Piezo1 can be activated by chemical activators, while Piezo2 has not been reported to respond to chemical activation [28]. These lines of evidence strongly suggest that Piezo1 might serve as a polymodal sensor of diverse forms of mechanical forces, whereas Piezo2 could be more narrowly tuned to detect specialized mechanical forces.
Restoration: Nanotechnology in Tissue Replacement and Prosthetics
Harry F. Tibbals in Medical Nanotechnology and Nanomedicine, 2017
Mechanical magnetic sensors include geometric magnetometers, where the sensor is moved or deformed by interaction with the magnetic field, and resonance sensors, whose vibration rate is influenced by field forces [227]. Electronic sensors include Hall effect sensors [228], which measure the resistance to flow of electrons caused by their deflection in a magnetic field; magnetoresistive, giant magnetoresistive, and colossal magnetoresistive sensors, based on thin-film conduction effects (the 2007 Nobel Prize in Physics was awarded to the discoverers of giant magnetoresistance, Albert Fert and Peter Grunberg) [229], and flux-gate devices, which compare the difference in current required to magnetize a coil in two directions. Some sensor designs utilize more than one physical effect in the same device for enhanced performance. Quantum sensors include the superconducting quantum interference device (SQUID), based on Josephson junction currents—the magnetically sensitive tunneling of electrons through a thin insulating barrier separating two superconductors [230].
Dynamic intracochlear pressure measurement during cochlear implant electrode insertion
Published in Acta Oto-Laryngologica, 2019
F. Ordonez, C. Riemann, S. Mueller, H. Sudhoff, I. Todt
The ICP was measured using a micro-optical pressure sensor FOP (FISO, Canada). The tip of the pressure sensor is a hollow glass tube sealed on one end by a thin plastic film diaphragm coated with a reflective surface of evaporated gold. The optical fibre is located in the glass tube with a short distance (50–100 μm) to the diaphragm tip. The optical fibre is attached to an LED light source and to a photodiode sensor. Light from the LED source reaches the sensor tip of the optical fibre, fans out as it exits the fibre, and is reflected by the gold-covered flexible diaphragm. The photodiode senses the reflected light, and small pressure-induced distance displacements of the diaphragm modulate the intensity of the reflected light. The sensor is connected to a module that is linked to a computer. Evolution software was used to record the ICP. The time sensitivity of the sensor was 300 measurements per second.
Discovery of RNA-targeted small molecules through the merging of experimental and computational technologies
Published in Expert Opinion on Drug Discovery, 2023
Characterizing the kinetics of binding can lead to an understanding of the efficacy and safety of the small molecule and therefore enhance the success of the drug discovery program. SPR is the most extensively used technique for measuring the kinetics of small-molecule binding to an RNA [144]. In an SPR experiment using a microfluidic system, the target biomolecule (RNA) is immobilized onto a sensor chip, and a pump is used to flow the liquid containing the ligand (small molecule) over the sensor chip (Figure 4(b)). An optical system measures the changes in refractive index at the interface of the liquid and the sensor, which are plotted over time in the form of a sensogram. From the SPR experiment, one can obtain the kinetic parameters, such as the association and dissociation rate constants (kon and koff, respectively) and KD. SPR is highly sensitive, relatively high throughput, and has a small sample requirement. However, the target immobilized onto the sensor must be stable over time, and a high level of expertise and experience are necessary for carrying out a successful SPR experiment.
Investigation of two-body wear behavior of zirconia-reinforced lithium silicate glass-ceramic for biomedical applications; in vitro chewing simulation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Ceramic and composite specimen’s 3 D and 2 D profilometer images were taken and analyzed for volume loss on the wear surfaces after chewing tests (using noncontact profilometer Bruker-Contour GT 3 D). Wear volume loss and depth of the test specimens were determined with a spacing of 8 µm at x-axis, 12 µm at y-axis and 1000 µm/s measurement speed scanning on the wear surface using noncontact profilometer (Bruker-Contour GT 3 D Vision64 simulation software). The wear surfaces of the ceramic and composite specimens were sputtered with gold and SEM images were taken after chewing simulation tests (ZEISS SIGMA 300). The wear analysis in biomaterials is evaluated with many different methods such as a contact or noncontact profilometer device, digital microscope, optical sensor, and laser scanning. A study in literature evaluated the variables of volume and vertical loss using different methods such as profilometer, optical sensor and laser scanning (Heintze 2006). As a result, it has been found that the volume loss of the surface wear area in both the wear depth and lateral axes is significantly related to each other. In this study, wear analyzes were performed using 3 D noncontact profilometer device and the wear area in wear depth and lateral axes were related to each other. The advantage of using this method was the analysis of wear depths and tracks in the wear areas of the test specimens.
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