UDRI and YSI, Inc. Collaborate in Chemical Sensor Development

In January 2003, YSI, Inc. (based near Yellow Springs, Ohio) announced an advance in sensor systems used in cell culture monitoring by the biopharmaceutical market. YSI, founded in 1949, boasts a long list of industry firsts in sensor products, but drew upon the expertise of Senior Research Scientist Jay Johnson and his Sensors Laboratory at the University of Dayton Research Institute in order to make their latest advance.

YSI’s Life Sciences unit offers a number of innovative, sensor-based products to meet research and development and production needs in the food, health care, and biopharmaceutical industries. In the fall of 2001 YSI introduced a modular and flexible measurement platform, the YSI Model 7100, which was targeted to the cell culture and fermentation segment of the biopharmaceutical market. This analyzer could be configured to measure four of the critical parameters in cell culture monitoring: glucose, lactate, glutamine and glutamate. The 7100 is based on the well-established enzyme electrode technology originally developed and commercialized by YSI in the mid-1970s.

In 2001, YSI asked Jay Johnson to help them further improve the Model 7100. YSI wished to add the capability to measure the remaining critical parameter for cell culture monitoring: ammonium ion. Monitoring the ammonium ion concentration is critical in cell culture because it is a waste product of cellular metabolism that can be toxic if it is allowed to increase above certain levels. In general, the only way to keep the ammonium concentrations below toxic levels is to replace the growth media when the ammonium concentration starts to approach some predetermined, maximum allowable level. Growth media can be very expensive, so the need to measure ammonium is driven by the economic need to replace the media only if necessary. At the same time, YSI wished to hit performance and cost-per-test targets that were at least equivalent to those realized in similar analyzers currently offered by YSI’s competitors.

Dr. Johnson went to work to develop a new ion selective electrode (ISE) module for the 7100 that could be used to measure both ammonium and potassium ions. (Potassium ion must be measured because it interferes with the ammonium ion measurement.) According to Dr. Johnson, “ISE technology is nothing new but it had not been used previously in any of the analyzers developed by YSI Life Sciences. Our job at UDRI involved working with an original equipment manufacturer of ISEs to physically configure them for the fluidic chamber of the analyzer. We also developed the prototype electronic board, developed and verified the associated reagents and software algorithms, and verified the performance. We then transferred the technology to YSI and worked closely with them as they completed the final integration of the ISE module into the 7100 system.”

Chris Tarpley, Vice President and General Manager of the Life Sciences Group at YSI, considers this collaboration to be a great success: “The additional capability to measure ammonium with the 7100 is an important milestone for us. Many customers have asked YSI for this because there are few good alternatives for this measurement. Combined with the 7100, the customer can now get a full suite of data on the six parameters considered to be the most important in the cell culture and fermentation process. The technical expertise that Jay Johnson and UDRI brought to the project simply made the difference in having it or not having it.”

While YSI continues to improve the ISE reagents, software and electronics developed at UDRI, the enhanced 7100 measurement system met its performance objectives and was introduced to the market in late January of this year. YSI has found the initial customer feedback to be quite encouraging, and UDRI and YSI expect to work on more collaborative projects in the area of biosensor research and development in the future.

For more information, please contact Jay Johnson at UDRI at 937-229-2569, or Chris Tarpley at YSI, Inc. at 800-765-9744.

February 28, 2003