Sunday, May 28, 2017

Cell Culture Incubators - They Sure Don't Make 'em Like They Used To

cell culture incubators
Cell culture incubators
Courtesy Esco
Incubators have been a mainstay of many applications in life science research and clinical testing for many many years. The term incubators can refer to a broad range of manufactured products, but let us narrow the focus of this article to equipment used for cell culture.

Equipment from decades ago was primitive when compared to what is available today. One early model sported all copper construction, not to impede contamination, but to enable its construction method using soldered seams. This particular water jacketed incubator was also heated by a gas flame and used a mercury filled temperature switch to control temperature within a few degrees of a setpoint.
Why were incubators water jacketed?
There were two valid design reasons for building a water jacketed cabinet. Early on, heating options were practically limited by cost and capability to the delivery of heat in concentrated areas. Since temperature uniformity throughout the work zone is probably the most important performance consideration for an incubator, it was necessary to evenly disperse the concentrated heat throughout the chamber in a manner that did not create undesirable variance. One way to accomplish this was, and still is for some manufacturers, to surround the chamber with a water filled "jacket". The water served as a heat distributor through natural convection.

The second reason for water jacketed design is to provide an interior environment with very little air movement. With all the chamber wall surfaces maintained at the same temperature, the heat input to the work space is uniform, and robust air circulation to provide an even temperature distribution is not needed. Air movement tends to promote desiccation in cell culture media, so lower air movement is generally better. Many cell culture operations also require very high levels of relative humidity, and lower chamber air movement will tend to promote a higher moisture level in the contained space. It was common to place a tray of water in the base of the chamber to saturate the air.

Not surprisingly, manufacturers continually strive to improve their products. New or improved technologies for measurement, control, or construction related to incubator design eventually reach a price point that enables their practical incorporation as a product improvement. Improved temperature controllers, sensors, and heater designs have enabled the production of incubators that deliver performance comparable or superior to water jacketed designs, but without the water jacket.

To grow, cells have the same needs today they had decades ago. Manufacturer's application of technological improvements to continually enhance their products has provided real benefits to researchers and other users of cell culture incubators. Higher reliability and lower requirements for attention from the user has increased lab efficiency.

Get more information about the useful features incorporated in the latest cell culture incubator designs from product specialists. Share your concerns and challenges with them, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Monday, May 15, 2017

Environmental Chambers - Difference Between an Alarm and a Limit Control

walk-in controlled environment room
Walk-in Controlled Environment Room
Courtesy Percival Scientific
Users of controlled environment equipment are generally not process control experts. The user's interest in the equipment is, and should be, focused on how it furthers their own work and effort.

Lab equipment that provides a temperature control function will often have an integrated heating or cooling means that is regulated by the unit controller. Controlled environment chambers, including benchtop, floor standing, and walk-in types often are provided with sufficient heating of cooling capacity to do damage to the equipment, the contained product or work materials, even surrounding spaces if allowed to run out of control. Why so much power? Designing a chamber of any size to provide fast recovery after a disturbance, like a door opening, will boost the capacity requirements for the heating and cooling portions of the system. Similarly, equipment with extended temperature range is likely to have expanded cooling or heating, and there are many other performance requirements that have the same impact on the unit capacity. The key element for placing this type of equipment in an occupied space is how malfunction resulting in uncontrolled operation of the environmental conditioning system is handled to prevent catastrophe.

An alarm is an annunciation of an adverse condition. Alarm function may be, and often is, provided as part of the temperature controller, utilizing the same device, same sensor. Alarms tell the operator something has gone wrong, is about to go wrong, or is currently going wrong. The nature of most alarms allows the user to set the conditions at which notification occurs. Additionally, some equipment provides options for how alarms are handled. Audio and visual indication are common features, and some equipment is provided with alarm relay contacts that can be connected to building management systems or other remote monitoring equipment. Whether an alarm will automatically reset if proper conditions are restored, or manual intervention is required to stop any alarm related activity once the alarm has occurred can also be different ways in which alarm functions are implemented by manufacturers. The overall range of alarm functionality combinations is extensive, with some equipment providing richer feature sets than others.

Alarms, in some controlled environment systems, are configured to take some sort of action to remediate the adverse condition. This activity is separate from the announcement of the alarm condition. While having corrective action taken by the control system may seem advantageous, and in some cases it may help prevent loss or damage to product contained within the environmental chamber, this is not true limit control action and is not the best practice for assuring safe operation of machinery with the capacity to do real damage to itself or surrounding spaces.

A limit control may appear at the user interface level to mimic the function of an alarm. There is a difference, though. Properly done, a limit control operates with total independence from any part of the regular temperature controller. The limit controller will be a separate device and not share any operating hardware with the temperature controller device chain. What does this mean for the user?

Relying on the temperature controller to respond to an adverse condition has some potential flaws. The temperature controller, or any of the components in the temperature control device chain, could be the root cause of the adverse condition through malfunction or outright failure. Reliance on a control circuit, likely with a malfunction of one or more of its components, to prevent further temperature excursion is not good practice. A properly designed limit control circuit does not rely on any of the components in the potentially failed circuit to stop heating or cooling.

Not all failures are a single event. Chains of failure can trigger, or one failure can expose the existence of another system weakness or failure that was previously undetected. Having a positive and independent means to reliably stop system operation is not costly to implement and can head off catastrophes resulting in substantial loss of time and money. Catastrophe, for an environmental chamber, can look like this...
  • Freezing of product that should not be frozen
  • Freezing and bursting of pipes in a walk-in chamber
  • Destruction of work or product contained within a chamber due to excessively hot or cold temperatures
  • Excessively hot temperature that activates a fire protection sprinkler head in walk-in unit
In essence, the purpose of an environmental chamber is to create and maintain a single condition at any point in time. There is only one way that things can go right, and countless ways they can go wrong. Having an independent watchdog controller that prevents the worst from happening is good practice. Share your controlled environment chamber requirements and concerns with an application specialist. The combination of your process knowledge and experience with their product application expertise will yield an effective solution.

Friday, May 5, 2017

Lab Planning - Everything is Connected to Everything Else

laboratory design planning meeting
Each participant brings value to the lab planning process
Lab planning, whatever the scale, benefits from participation by specialists in the various facets of the project. Nobody knows everything, so collaboration and coordination are needed to balance and satisfy the wide array of jurisdictional, institutional, scientific, and other requirements that make up a successfully completed project.

Lab space is comparatively expensive to create or renovate. Architectural, mechanical, electrical, or other items will be incorporated into the space that may not have applicability to future use of the square footage other than as a laboratory. A long term view of the space dedicated to laboratory use and the incorporation of features and structures that can support that long term use can be beneficial.
What are some of the facets and drivers of the lab planning process?
Safety - Most are familiar with common laboratory safety and sources of hazard. Arranging the work areas and equipment, coordinating personnel movement, and other considerations can serve to reduce the potential for mishaps. The details are far beyond the scope of this article, but keeping safety in mind and a knowledgeable safety specialist on the planning team will deliver benefits every day the lab is in operation.

Productivity - The arrangement of workstations and equipment can have a cumulative impact on how much work gets accomplished in a given time frame. Productivity improvements are most often achieved in very small increments, many of which, combined, add up to real gains.

Ergonomics - Lab work can entail precise manipulation of instruments and tools, as well as visual inspection or interpretation of ongoing processes. Maintaining a level of technician comfort will promote productivity and safety, as well as reduce the potential for errors. Participants in the planning and design process knowledgeable and experienced in ergonomics can add to the overall success of the project.

Facilities and Utilities - Lab spaces often have unique requirements for electrical and mechanical services and support. It can be beneficial to make an attempt to accommodate potential future uses of the space for lab processes other than the initial intended use. Air supply and exhaust, electrical service, plumbing specialties, and more can be initially installed to support a variety of future endeavors. This foresight could avoid disruption of surrounding spaces and excessive cost to make changes in the future.

Budget - The budget drives stakeholders to place a value on almost every facet and detail of the project. A careful weighing of the benefits derived from every part of the design puts discipline into the process and can lead to a positive outcome.

A great plan arises from the combination of many participants. Share your laboratory planning challenges with experienced professionals, combining your own knowledge and experience with theirs to produce an effective solution.