Developments being made in laboratory heating and cooling systems are often overlooked, but they remain a mission-critical contributing factor to the success of clinical laboratories. Clinical labs often face pressure to automate operations, manage increased workloads, and reduce budgets, all while recruiting experienced technical staff. New heating and cooling technologies help address those pressures by being responsive to current needs and supportive of the future demands of clinical laboratories.
Advances in heating and cooling equipment used in the clinical laboratory environment improve biological sample security. New approaches to research have impacted, and will continue to change, how researchers utilize these technologies in their laboratories. Important types of heating and cooling systems, such as ultra-low temperature (ULT) freezers, advanced lab refrigerators, and incubators, ensure temperature consistency and sample integrity. Some new technologies that support innovation in laboratory systems are wireless monitoring/remote sensors, dual convection technology, and advanced microprocessor controls.
Wireless monitoring and remote sensors in ULT freezers
Wireless monitoring solutions have become an indispensable solution for ULT freezers, blood bank refrigerators, and plasma freezers. These solutions safeguard the integrity of laboratory samples through continuous, 24/7 monitoring of key measurements such as temperature, CO2 concentration, and relative humidity. Data collection is uninterrupted and secure, and can be accessed via the Internet, providing scientists with a sense of security and peace of mind about their valuable biological samples.
In the event of a mechanical or electrical shut-down at the lab, these monitoring systems send a real-time alert to pre-assigned personnel that the integrity of biological samples may be at risk. There are several options for the delivery of these alerts, including alarm notification via fax, telephone, email, or text message. On-site lab security personnel can receive audible or visual alarms calling them to investigate the situation, while off-site personnel can monitor the resolution of a false alarm without having to return to the lab.
For quality control purposes, samples have traceability via an audit trail created by the wireless monitoring system. The system also conforms to 21 CFR Part 11, the FDA guideline on electronic records that defines the criteria necessary for electronic records and electronic signatures to be trustworthy, reliable, and equivalent to paper documents.
For clinical environments, typical storage requirements call for lab refrigerators to maintain a +1°C to +8°C temperature range, and lab freezers to maintain a range of -20°C to -30°C. These precise ranges are required for vaccines, whole blood, plasma, chromatography, enzymes, and other temperature-sensitive materials. For applications requiring ultra-low temperature ranges, interfaces in newer ULT freezers allow the user to check the internal conditions of the freezer without having to open the door, which can expose samples to ambient temperatures. Having a reliable cold storage product with the latest technological advances protects critical lab samples.
Dual convection technology in microbiological incubators
Dual convection technology is an advance that combines the benefits of gravity and mechanical convection in a single microbiological incubator. Multi-mode convection equipment lets the scientist decide which convection method manages the biological samples to be processed within the incubator, ensuring reproducible conditions for the growth of microorganisms.
Wireless monitoring solutions provide continuous monitoring of laboratory equipment with remote alarm notification and continuous data collection.
A mechanical convection incubator incorporates a fan that actively forces heated air through the chamber. The fan creates airflow that provides even temperatures with high accuracy (± 0.2°C) and fast heat-up times. Tight temperature uniformity ensures a stable temperature environment for specific cells or microorganisms. For example, in ISO 6579, for the detection of Salmonella spp. in food,1 the first stage in traditional detection methods is usually a pre-enrichment culture in a nonselective liquid medium, such as buffered peptone water, which is incubated at 37oC for 18 hours. The pre-enrichment culture is then subcultured into another selective enrichment media, such as Rappaport Vasiliadis Soy broth (RVS), and incubated for an additional 24 hours at 41.5oC. Biological samples that require temperature uniformity during incubation support the use of mechanical convection incubators.
The fast heating feature of mechanical convection stimulates growth of samples more quickly, as seen when directly transferring samples from a refrigerator. Care must be taken to avoid high evaporation rates, which impact samples and nutrient solutions. Evaporation rates lead to dehydration of samples: the higher the evaporation rate, the higher the risk of drying, especially in longer experiments. The resulting concentration of remaining nutrients can also be detrimental for growth.
When using the gravity convection feature of a microbiological incubator, temperature distribution is based on warm air moving upward, although there is no fan to actively distribute air inside the chamber. Temperature uniformity within the chamber is achieved by the design of airflow from the heating elements through the inner chamber of the unit. The benefit of the gentle airflow is a reduction in the dehydration of samples when working with vented plates or during long incubation cycles. This was demonstrated in a recent study2 in which researchers examined Legionella pneumophila strain densities as measured by colony forming units (CFUs) by serially diluting and plating a small aliquot of the bacterial suspension on buffered charcoal yeast extract (BCYE) agar plates. Plates were successfully incubated for 48 hours at 37°C, and Legionella colonies were counted. Legionella strains may require long incubation times, and are better supported by gravity convection incubators.
Advanced microprocessor control in laboratory refrigerators
Appropriate temperature control solutions are vital to reliable, consistent, and accurate results, so that all laboratory applications can run consistently, efficiently, and effectively. Advanced microprocessor controls are at the forefront of lab refrigerator technology and are constantly evolving.
Temperature fluctuations are the enemy of valuable samples. Variability in conditions can damage samples and may be undetectable or unpredictable with older models of lab refrigerators and freezers. New advances in laboratory refrigeration provide the security and protection necessary for high-value samples.
On certain models, the user interface (UI) of the lab refrigerator can be configured to provide improved management of storage conditions for samples. Some of the newer UI features include international icon-based controls and displays, enabling universal recognition by researchers. A graphic thermometer allows researchers to confirm proper operation of the lab refrigerator with a quick glance, and a “Service Required” alarm alerts lab staff when maintenance is necessary to support optimal performance.
New technology in setpoint security is available, with some models running via a key-operated, triple-position switch that locks in temperature and alarm setpoints. This technology minimizes setpoint error and prevents tampering. A touchpad allows access to control function defaults for maintenance, troubleshooting, or data entry to increase or decrease setpoint values when in programming mode. Touchpads can change the data displayed in the UI or allow access to programming and service functions such as alarm muting. The Alarm Test function allows the user to simulate over-temperature and under-temperature conditions. Activation of audible and visual alarms occurs when the test is complete. Audible and visual indicators are activated in the UI if the warm alarm threshold or cold alarm threshold is breached or when power-loss conditions occur. A digital UI can indicate cabinet temperature conditions, displaying normal operation or alarm conditions, to notify researchers when the lab refrigerator door is ajar or when the backup battery for the display needs to be checked.
Additional features improve ergonomics, efficiency, and energy savings. Flush-mounted light switches allow for ergonomic operation; self-contained control housings can be integrated into the main control panel for efficient maintenance; and some models offer mercury-free LED interior lighting for improved visibility. Routine maintenance is enabled by the microprocessor control system.
Regular upkeep and repairs can often be facilitated through the front of the lab refrigerator or freezer, making it easy for the biomedical engineer to gain access and service the unit without impacting the application. This ensures that laboratory routines are not interrupted by the need to pull the laboratory refrigerator unit out of a cabinet or from under the lab bench to perform repairs, getting in the way of efficiency.
Even as so much has changed in the clinical laboratory in recent decades, protecting valuable biological samples has remained one of the biggest challenges laboratorians face. Advances in heating and cooling technologies, combined with superior materials and components, allow them to perform delicate tests with confidence that their samples are safe and protected, producing accurate and reliable results.
References
- Salmonella detection and identification methods. http://www.rapidmicrobiology.com/test-methods/Salmonella.php. Accessed April 4, 2013.
- Buse HY, Ashbolt NJ. Differential growth of Legionella pneumophila strains within a range of amoebae at various temperatures associated with in-premise plumbing, Letters in Applied Microbiology. 2011;53:217–224a
