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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of ...
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Novel technique to observe nanoparticles in a liquid environment

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The macroscopic effects of certain nanoparticles on human health have long been clear to the naked eye. What scientists have lacked is the ability to see the detailed movements of individual particles that give rise to those effects.


  • This technique will allow, for the first time, the imaging of nanoscale processes, such as the engulfment of nanoparticles into cells.
In a recently published study, scientists at the Virginia Tech Carilion Research Institute invented a technique for imaging nanoparticle dynamics with atomic resolution as these dynamics occur in a liquid environment. The results will allow, for the first time, the imaging of nanoscale processes, such as the engulfment of nanoparticles into cells.

Nanoparticles are made of many materials and come in different shapes and sizes. In the new study, Kelly, an assistant professor at the Virginia Tech Carilion Research Institute, and her colleagues chose to make rod-shaped gold nanoparticles the stars of their new molecular movies. These nanoparticles, roughly the size of a virus, are used to treat various forms of cancer. Once injected, they accumulate in solid tumors. Infrared radiation is then used to heat them and destroy nearby cancerous cells.

To take an up-close look at the gold nanoparticles in action, the researchers made a vacuum-tight microfluidic chamber by pressing two silicon-nitride semiconductor chips together with a 150-nanometer spacer in between. The microchips contained transparent windows so the beam from a transmission electron microscope could pass through to create an atomic-scale image.

Using the new technique, the scientists created two types of visualizations. The first included pictures of individual nanoparticles’ atomic structures at 100,000-times magnification – the highest resolution images ever taken of nanoparticles in a liquid environment.

The second visualization was a movie captured at 23,000-times magnification that revealed the movements of a group of nanoparticles reacting to an electron beam, which mimics the effects of the infrared radiation used in cancer therapies.

In the movie, the gold nanoparticles can be seen surfing nanoscale tidal waves.

The team is also testing the resolution of the microfluidic system with other reagents and materials, bringing researchers one step closer to viewing live biological mechanisms in action at the highest levels of resolution possible.