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Dec
29

The Real Deal with Wet Labs

My first experience with wet labs was about 35 years ago when I set up an acetic acid and water neutralizer and distillation column with conductivity, flow, level, pH, and temperature loops as part of a 6 week course to teach process control to new employees. I learned first hand how time consuming and expensive it is to set up and keep a lab running in top notch condition. Any compromises in hardware lead to headaches. I handed this off to someone willing to make the lab and the course a full time job.

About 10 years later, I managed to get a research technician to set up a lab to test pH electrodes from 9 different manufacturers. We got a lot of data on the effect of salt concentration and temperature on electrode performance but we had headaches with algae growth and dealing with undocumented features. The flat glass electrode developed large errors as the temperature and slat concentration was increase. Solid reference electrodes had acceptable performance but were not as accurate as some gel double junction electrodes. It would have been nice to study the effects of coating but the consequences in terms of cleaning out the equipment and lines were prohibitive. The lab was only used for one year but this still represented a cost of probably $50K in time and material. In retrospect, we should have studied the effects of velocity and mixing. I would love to have a lab today that is better than my 1980s lab to study the performance of new electrodes, diagnostics, and wireless reporting. It seems to me there is less information today than 20 years ago on the effect of process conditions on pH electrode performance. pHwetLab

While teaching a course on process dynamics and control at Washington University (WU) in Saint Louis, I was asked to teach a digital computer control lab for systems engineers. The lab was mostly a collage of instrumentation, valves, and controllers you would never see in industry. I arranged for the donation of the latest Fieldbus smart transmitters and smart control valves and a “state of the art” DCS system by Emerson. While teaching the lab would be neat, I knew from previous experiences it would an intensive effort that would take away from teaching, studying, and writing on modeling and control using the virtual plant I had set up at WU for my course for Chemical Engineers. Luckily I found the perfect choice in Bob Heider who enthusiastically has kept the lab in great shape and taught a course of great practical value for the last 5 years. The lab is unique in that engineers are taught how to calculate and evaluate process dynamics on a first principle basis.

My most recent experience is initiating and guiding a wet lab for bench top and single use bioreactors (SUB). Fortunately, Broadley-James Corporation (BJC) has committed the resources to make this happen. As with all process research labs, especially bio-reaction labs using new analyzers, cell lines, and media, strict schedules are an impossibility particularly considering this is an extracurricular effort for BJC. We have suffered from prototype sample system and analyzer failures, an NIR probe company going bankrupt, media problems, cell line discontinuation, infections, and delivery delays. Despite the slow progression, we have adjusted the virtual plant’s model growth, death, and substrate kinetics to better match the lab runs and have tested closed loop glucose control, which is essential for an effective design of experiments (DOE) for parameter identification. We are also now testing wireless pH and temperature control on the SUB. PATLab

A successful wet lab requires patience, enthusiasm, and a focused “care taker.” The practical experience and data gained for the development of sensors, control strategies, and dynamic models is well worth the effort. Experimentation in a wet lab can be more effective and is certainly much less expensive than experimentation in an actual plant even if permitted.