SI-H Cell Tester Opens a New Window to Cellular Studies

Posted: Wednesday, April 24, 2013


New technologies developed by SI-H offer incredible opportunities for muscle physiology researchers. Up until now, many studies required an entire day to perform aSI-H Cell Tester single trial. Now, after isolating the cells, these same studies can be run on single cells in a matter of minutes. Because we are working on single cells, we can test living organisms. Tetanus, cardiac work loops, afterload and constant load contraction studies, calcium imaging, sarcomere spacing, NAD/NADH and FAD/FADH studies can all be performed on a single cell with the SI-H CTS200 Cell Tester system. According to Dr. Harm Knot (staff muscle physiologist), “The new Cell Tester, a novel cell biology research tool, is set to revolutionize the emerging field of ‘mechano transduction’ by allowing researchers to study the influence of mechanical force, stress or strain on cells and how these cells react to stimuli.” The Cell Tester opens many new avenues of research, including the possibility of clinical studies on live human subjects.
Because of the elegant design of the SI-H line of muscle physiology systems and the advancements in LED technologies, the price of SI-H research systems is significantly reduced when compared with the older systems in the field right now. The SI-H systems are modular in design, allowing you to choose the options you need immediately with the flexibility of adding to the system in the future when your needs change.

First, let us consider the Cell Tester platform and some of its accessories. Then, we can look at some of the popular options, including the Biofluorometer for calcium imaging and the new Optical Sarcomere Spacing System.


Cell Tester Features

The Cell Tester is comprised of a pair of piezo micromanipulators with a nanomotor attached to one and a KG optical force transducer on the other. It features a platform-independent rotational stage that fits on any inverted microscope. In addition, the system includes a complete electronics package that includes the Position Controller that also has tweezer controls, the Temperature Controller, the SI-BAM21 Optical Force Transducer Amplifier and the Anti-Oscillation module. The Constant Load module is an available option, and the Afterload module will soon be released. For calcium imaging studies, NAD/NADH or FAD/FADH studies, the Biofluorometer is available with application specific probes. Soon, the Optical Sarcomere Spacing System will also be released for use with the Cell Tester. The beauty of the Cell Tester is its streamlined design. The electronics fit into a single box, and the Cell Tester itself takes precious little lab bench real estate.

The heart of the system is a tuned and paired combination of a linear actuator offering nanometer (nm) precision and a force transducer with nanonewton (nN) sensitivity. Each element (actuator and sensor) is equipped with a remote controlled micro-tweezer that allows tissues to be held firmly.

SI-KG series optical force transducers measure a large range of detectable forces. The transducer with the highest sensitivity (20nN) is sufficient to measure the force of a single heart cell. That is the SI-KG7 force transducer, the one used with the Cell Tester. Because all the SI-KG transducers are extraordinarily rugged, withstanding even overload forces, they come with a lifetime warranty.

The same Cell Tester platform can be used for both mounting the cells and conducting the experiment, streamlining the entire process. You can use the Cell Tester to measure length and affect force, BUT it is also a mounting device that really works on a single cell. The rotational stage bath is designed to orient cells in the XY plane so that no physical manipulation of the position of the cell itself is required prior to capture by the tweezers attached to the force sensor and linear actuator. This bath has two interchangeable inserts. The first holds any (disposable) 35mm glass bottom dish (for example, WPI #FD35-100 FluoroDish). When coating tweezers or glass rods with a bio-compatible adhesive, insert a disposable FluoroDish into the holder and place it in the rotating cuvette. When finished, remove the insert and dispose of the FluoroDish . Then, position the native cuvette insert containing the live cells. If you prefer, you can use another FluoroDish for the live cells. This elegant design of the rotational stage simplifies the cell mounting process.

Because the system includes the SI-TCM2 2-channel Temperature Controller, there is no need for circulating water in the rotational stage. That means you have less equipment on your laboratory bench and the potential for fewer spills on your microscope stage and nearby electronics.

The optional Constant Load module can clamp the load to the sarcomere length, the force exerted by the muscle cell or any other measurable parameter. The optional Afterload unit allows you to conduct cardiac work loops with single cells and a range of biometrics that previously required intact tissue.

The SI-CTS200 Cell Tester platform can accommodate many muscle physiology experiments right out of the box. And, with the addition of accessories like Constant Load or Afterload units, the Biofluorometer and the Optical Sarcomere Spacing System, you can perform ALL the classic muscle physiology experiments on a single cell, including cardiac work loops.



The new SI-BF100 Biofluorometer is an LED-based fluorometer for life science applications. It is ideally suited for ratiometric calcium detection (using FURA-2, FLUO-3, FLUO-4, Calcium Green 1…) and ATPase detection (via NADH fluorescence). This equipment is more affordable than the cumbersome models of yesteryear. Recent advancements in optics and LED technology have radically simplified ratiometric calcium imaging. And, a breakthrough in WPI patented technology allows theSI-BF100 to use wavelengths below 380nm and produce more light in those spectra. This technology significantly cuts the cost of photometric calcium imaging without sacrificing resolution or quality.

Up till now, calcium imaging systems have been required to compensate for errors and noise introduced by the complexity of their design. The old systems required mechanical filters and used expensive xenon or mercury light sources. The beauty of the SI-BF100 is its simplicity. The elegance of its design reduces the noise introduced into the system and the errors inherent in traditional designs.

Monochromatic LED light sources using WPI patented technology eliminate the need for complex and expensive white light sources and filter wheels. Because the LED modules can be pulsed, sampling frequencies up to 1,000 cycles per second are possible. The LED light source emits specific excitation frequencies which travel through the probe. The excitation light can be comprised of any wavelength of light for which an LED module is available. The probe returns a single emission output to one or two photomultiplier inputs on the front of the SI-BF100, which are independently filtered for specific wavelengths. This design allows you to monitor multiple wavelengths from a single emission output.

The LED light source in the WPI design makes this ratiometric fluorometer more compact, energy efficient and affordable. The low-power light source produces much less heat, and it warms up in less than one minute! Traditional xenon or mercury light sources require 20–60 minutes to warm up. As an added bonus, the typical LED bulb lasts over 10,000 hours. Mercury and Xenon bulb experience wild fluctuations in light intensity. Whereas, the LED light is by nature incredibly stable. Even so, the SI-BF100 uses a separate reference channel, so that the ultra-stable, continuous ratio calculations automatically compensate for any LED light intensity drift. This feedback control monitors the actual light output. This ensures less noise and produces more accurate measurements.

This incredible design is not limited to calcium imaging either. By simply replacing the emission filter in front of the photomultipliers with the desired wavelength filters, your SI-BF100 becomes a general purpose fluorometer for any application you can imagine. Changing a filter is as simple as removing the two screws that hold the filter carriage on the face of the SI-BF100, swapping the filter and reinstalling the integral SMA/filter carriage.

The application-specific probes for the Biofluorometer are available for the existing SI-H tissue baths and cuvette systems. Even better, the probe can be designed in any geometry for other applications.

The Biofluorometer is a novel and extremely flexible engine for singular wavelength, LED spectroscopy. It allows you to perform calcium imaging studies and conduct NAD/NADH and ROS measurements. In the near future, the SI-BF100 could become an optogenetics cellular engine where light of a particular wavelength is used to specifically target the cells under observation. Likewise, it will soon be possible to use it with fluorescent dyes in neuroscience applications or to measure free radicals (H202, H2S or any other radical for which there is a dye) in living cells. The Biofluorometer is a novel, LED-based spectrometer and light engine.


Optical Sarcomere Spacing

The SI-H Optical Sarcomere Spacing System for the Cell Tester will soon be released. The system includes a high speed microscope camera, the software necessary to measure and monitor the changing images, and an analog output for logging the data. The microscope camera, with a maximum rate of 1700 fps, mounts on your inverted microscope above the Cell Tester. The video images of the cell are fed into the software for analysis. The software is based on the open source, freeware “Micro Manager” from NIH. A custom plug-in allows the software to monitor sarcomere length, vessel diameter or any other feature on the images that is measured in microns. An analog output that is proportional to the sarcomere length (or measured feature) allows you to track your data in real time. If the Optical Sarcomere Spacing System is used in conjunction with the Constant Load module, the force exerted on the cell can be clamped to the sarcomere length. This opens up a host of experimental applications.

The incredibly flexible SI-CTS200 Cell Tester offers a window into cellular studies that have never been possible before. It is an open door on high throughput drug studies and studies on living organisms.


More Info

World Precision Instruments (WPI) has offices and distributors around the globe and has been serving scientists for more than 45 years. Muscle Physiologists on staff not only aided in the development of the SI-H line of products, but are also available to answer your questions. Feel free to send us an email at or give us a call at 866.606.1974.