Using SmartTrak 100 for Gas Mixing

Imagine being suspended in time - having metabolism reduce with a decrease in heart rate and a drop in temperature. Dr. David Kraus, Sulfide Biologist at the University of Alabama, points out that precision and linearity are very important. Dr. Kraus and other scientists are exploring how time can be bought in suspended animation by administering small amounts of H2S.

Measuring Gas Mixing in Mice

Dr. Kraus decided to take his experiments with H2S to a new level in 2005. It was during this time that Mark Roth, a scientist from the Fred Hutchinson Cancer Center, Seattle, was performing groundbreaking suspended animation experiments. Dr. Kraus set out to perform his own suspended animation experiments after being inspired by Roth's work.

Sierra's Solution

Based on Mark Roth's recommendation, Kraus came to a conclusion that SmartTrak® 100 was capable of delivering the precise amount of H2S to laboratory mice - too much H2S will result in killing the mice and just the right amount induces suspended animation, decreasing their metabolism and heart rate; virtually freezing their bodies in time. The animals "come back to life" following the removal of the H2S.

Most controllers are used for common standard-popular gases (nitrogen, argon, air). In his testing and research, Dr. Kraus employs a special blend of 5% hydrogen sulfide, 95% nitrogen with an extremely low flow range of 1 - 10 sccm, mixed into another stream of combined N2 and air mixture.

Dr. Kraus did have some concerns regarding the ability to carry out accurate measurements of mixed gases with the SmartTrak. Sierra's Laminar Flow technology was ideal for Dr. Kraus' custom blend application.

The SmartTrak's Dial-a-Gas® capability to program a custom listing for Dr. Kraus' 5% H2S blend could be used by technicians at the factory. In the laboratory, Kraus could then use the same instrument to measure any of the other nine pre-programmed gases or select this programmed mixture from the Dial-a-Gas menu.

Dr. Kraus' concerns about accuracy were well-founded. The SmartTrak 100 was required by his application in order to precisely maintain 1% accuracy from 0 to 10 sccm of H2S, an anesthetic gas. H2S has benefits when appropriately delivered but can also become poisonous, even lethal, when in excess.

With traditional mass flow controllers, gas mixtures are considered to be notoriously inaccurate. Most instruments are "curve-fit" to the application during calibration because they are not linear. They are calibrated with a primary gas; however, a gas mixture comprises of varied properties than the primary gas, hence the original curve is not correct for the mixture.

However, Sierra's Laminar Flow technology develops a linear relationship that allows the K factors programmed into the SmartTrak 100 to correct any gas blend over the entire flow range. The 100 is so linear that it is only calibrated at full scale and zero.

Dr. Kraus delivered small amounts of H2S to his laboratory mice in a precise manner by installing his 100s. This type of precision control and accuracy is provided by Sierra's powerful solenoid valve to the SmartTrak 100 even at the extremely low range of 1-10 sccm.

The toxic H2S gas did not lead to the death of any mice and all his subjects reached suspended animation, a SmartTrak 100 success.

Dr. Kraus, just like Mark Roth, observed a suspended animation-like state in his laboratory mice. Their heart rates reduced from 650 to 50 beats per minute and their breathing rate dropped from 140 to 20 breaths per minute. A decrease was also observed in their core body temperature and metabolic rate, suspending their body in time.

The mice came "back to life" when the H2S was removed. Dr. Kraus states that these suspended animation breakthroughs will modify the face of the medical field. He believes "this may be one of the most important medical breakthroughs of this century."

In 2007, a MacArthur Genius Award was received by Dr. Roth for his work with H2S induced suspended animation using the Sierra SmartTrak 100.

Sierra SmartTrak 100

Sierra's SmartTrak 100 is considered to be an ideal choice because of the following features:

  • Provides flexible and smooth valve performance
  • Has more robust electronics compared to other industry mass flow controllers
  • Patented, inherently linear Laminar Flow Element (LFE) design
  • Pilot module allows users to switch between 10 pre-programmed gases, modify engineering units, set zero, span and full scale, choose output signal, change setpoint value and source, and much more



This information has been sourced, reviewed and adapted from materials provided by Sierra Instruments.

For more information on this source, please visit Sierra Instruments.


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