Light Engine - Turning Light into Science
If you have seen a rainbow, you have seen the visible part of the light spectrum spread out. Each color we see is actually a different wavelength of light. In scientific applications, we are often interested in only one or two wavelengths of light. For example, a muscle tissue can be stained with Indo-1 or Fluo-4 causing intra-cellular calcium to fluoresce when excited by the appropriate wavelength of light. Or, a neuronal cell can be stained with di-4-ANEPPS and di-8-ANEPPS, causing a fluorescent signal that corresponds with the firing of an action potential.
WPI’s new SI-BF-100 Biofluorometer is a light engine that generates quick pulses of light in one (or two) wavelengths and then detects back-reflected light of a different wavelength (or two). Scientists mount isolated muscle tissue in one of our SI-H Muscle Tester platforms, then treat the muscle with an appropriate fluorophore. Then, they use the Biofluorometer to excite the muscle tissue with monochromatic light. Compliments of a Stoke's Shift, any calcium in the muscle will then fluoresce at a different wavelenth. The Biofluorometer measures the intensity of the resulting light (using very sensitive PMTs), which indicate the calcium concentration. This information can be used to quantify the intracellular calcium present in the muscle in real-time.
Before the development of the Biofluorometer, traditional systems also measured the calcium, but were much more complicated and expensive. Our Biofluorometer emits only the one (or two) wavelengths of light that the scientist is interested in. The older systems used high-power lamps that contained the entire spectrum. Then, optical filters were used to isolate only the necessary wavelengths for the experiment. We use LED lights which last forever, are relatively inexpensive and generate minimal heat. The LED light is very stable, and the units are instantly ready for use. The xenon and mercury lamps from the outdated systems were expensive, needed to be replaced frequently and were hot to the touch. The heat generated made the light source relatively unstable. Plus, the expensive lights took 20-60 minutes to warm up before you could begin an experiment.
The Biofluorometer’s light engine is based on our LEDspec technology, but much of the magic of the Biofluorometer happens in the Biofluorometer's probe. We found a way to combine the light in the smaller wavelength range so that this device actually detects it properly. This wouldn’t have been possible a few years ago. This patented technology belongs solely to WPI. The probe has many thin, glass fibers that transfer the light. Each light fiber in the probe must be positioned correctly at just the right angle and length. Our master craftsmen (and women) build the probes to exact specifications.
The next time you see a rainbow, think of our Biofluorometer. While it was originally designed for muscle physiologists to measure calcium, its applications in neuroscience, optogenetics and other emerging sciences are limited only by the imagination.
The Biofluorometer probe on the left side of this image shows the individual light fibers. The ones on the outside are illuminated. On the right side of the image you are looking into a testing chamber called a cuvette. This one is mounted on our SI-MKB Muscle Tester. You can see a strip of muscle in the “window” of the cuvette. The Biofluorometer probe is on the back side pointed at the window. The red (back) and black (front) cone tips on the right side of the image are electrodes attached to conductive wires inside the cuvette that cause the muscle to contract whenever electricity is pulsed through them.