Since the use of PCR has become widespread in molecular biology and diagnostic applications, thermocyclers (also known as PCR machines or thermal cyclers) have become central to the success of many laboratories. This importance has led to a vast array of instruments becoming available on the market. But while this substantial choice can be beneficial, it can also make selecting the most suitable model for your needs more challenging. This article provides a guide to the features to look out for before purchasing a thermocycler.

Temperature accuracy and control

The main consideration when looking for a thermocycler is that it provides accurate and uniform temperatures. “In order to perform polymerase chain reaction, the temperature range and uniformity across the thermal cycler plate is crucial so as to allow consistent amplification on the samples across the 96-well plate,” Thomas Wu, Bravo Product Manager, Automated Solutions Business, Agilent Technologies, explains. Without this, the reproducibility and reliability of your experiments cannot be guaranteed, so look for reported well-to-well temperature uniformity before making any purchase.

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Other factors to look out for are rates of temperature change and hold times. Put simply, you need a thermocycler that can change temperature quickly and consistently hold that temperature before it changes again. Ramp rates are the time taken for a thermocycler to change from one temperature to another, but while many manufacturers report block ramp rates, the time taken for a sample to reach that same temperature can differ. “The ability to control sample temperature vs block temperature is critical to PCR success,” explains Pradeep Savanoor, Market Development Manager at Thermo Fisher Scientific. So consider sample as well as block ramp rates for greatest temperature accuracy.

Temperature optimization

The ability for temperature variation is also key and can greatly increase the speed of primer optimization. As well as instruments with independently operating heating blocks that allow different reactions to be run simultaneously, many instruments can now achieve multiple temperature variations across the same block. Look for a robust technology that prevents heat interaction between wells and enables a more precise “true” temperature gradient to be established—enabling single run optimization and greatly increasing your throughput.

Capacity and flexibility

Sample capacity is an important factor when making a purchase. When choosing a thermocycler, think not only about the number of reactions you want to perform, but also the type and size of sample container you will be using. Instrument flexibility is also important and considering how your research needs might change is vital to future-proof your purchase. As Savanoor explains, “Thermal cyclers should be flexible and modular, and able to support different block configurations.” Look out for interchangeable heating blocks that can accommodate different tube numbers and sizes in addition to plates, to provide flexibility and increased throughput when needed.

Savanoor adds that if throughput is a major consideration for your laboratory, looking for models that allow “compatibility with PCR automation equipment or liquid handlers,” is key—and can increase speed and accuracy while reducing hands-on time.

Connectivity and monitoring

The potential for connectivity and the ability for remote monitoring are also now major considerations. According to Oliver Glenn Hernaez, Global Product Manager, Life Sciences Group at Bio-Rad Laboratories, “The growing millennial user base and their affinity for technology,” mean that “modern PCR instrument features generally include cloud connectivity, remote setup, and instrument monitoring.”

In addition, some manufacturers have made even further innovations in accompanying software—offering users not only reaction parameter control, but also temperature logs and completion status reports, in addition to using predictive analytics to pre-empt problems before they occur. So, as Wu notes, “software control and its ease-of-use is another critical aspect technicians should look for in a thermocycler.”

Reliability, warranty, and support

Purchasing any equipment is an investment, so you want to ensure any thermocycler you are considering is reliable. As Hernaez explains, you should look for “a workhorse instrument that performs consistently, run after run.” While features such as reliability and durability can frequently be overlooked in place of other specifications, ensuring your thermocycler can withstand high levels of use is essential to guarantee it can meet your needs.

Considering product warranty and support is also important. “Instrument wear and tear is inevitable, and knowing that you can trust a brand to take care of you when the instrument requires service is just as valuable,” Hernaez notes. Think about the technical support and maintenance plans available to give you the peace of mind that help is on hand if your instrument goes down.

Other factors

Other factors you may want to consider include instrument size and the available footprint in your lab, noise levels, and an ergonomic design to improve user experience. With growing costs, power consumption and the price of on-going consumables are also worthwhile considerations to ensure running costs are achievable.

With an ever-increasing number of instruments on the market, choosing the right thermocycler for your needs can seem like a daunting task. But by carefully considering your requirements and budget, in addition to peace of mind factors like remote monitoring and technical support, you can make an informed choice. And as Wu, predicts, the future of thermocyclers is only set to expand with “companies increasingly gravitating toward a 384-well format to accommodate higher throughput especially in the NGS applications space.” So, watch this space…

Table. Comparison of Top Thermocyclers

CompanyInstrumentDimensions*User interfaceBlock formatsTemperature rangeMax ramp rateTemperature accuracyTemperature uniformity
Bio-Rad PTC Tempo 28 x 50 x 26  8” LCD touch screen display 96-well, deepwell 4-100° C 5° C /sec ±0.2° C at 90° C ±0.4°C well to well within 10 sec of 90°C
Bio-Rad C1000 Touch 33 x 46 x 20  8.5" graphical touch screen 96-well, 96-deep well, dual 48/48-well, 384-well 0-100° C 5° C/sec ±0.2° C at 90° C ±0.4°C well to well within 10 sec of 90°C
Bio-Rad S1000 33 x 46 x 20  LCD panel and keypad 96-well, 96-deep well, dual 48/48-well, 384-well 0-100° C 5° C/sec ±0.2° C at 90° C ±0.4°C well to well within 10 sec of 90°C
Thermo Fisher Scientific ProFlex PCR System 33 x 56.5 x 27.2  8.4" color thin film transistor (TFT) LCD 32-well 96 x 0.2 mL tubes, 96-well, flat block, 384-well 0-100° C 6° C/sec ±0.25° C at 35-99.9° C 0.5°C (30 sec after reaching 95°C)
Thermo Fisher Scientific VeritiPro 24.5 x 46.5 x 21.7  8" color TFT LCD 96-well or 384-well plates 0-100° C 6° C/sec ±0.25° C at 35-99.9° C <0.5°C (30 sec after reaching 95°C) 
Eppendorf Mastercycler X50s 27.5 x 43 x 33  Touch screen 96-well plate or 0.1 and 0.2 mL tubes 4-99° C 3° C/sec ±0.15° C  ±0.3°C at 95°C 
Eppendorf Mastercycler nexus gradient 25 x 41.2 x 32.1  LCD panel and keyboard 96-well plate or 0.1 and 0.5 mL tubes 4-99° C 3° C/sec ±0.2° C ±0.4°C at 90°C 
Analytik Jena Biometra TOne 96 G 26 x 43 x 24.1  Touch screen 96 x 0.2 mL tubes, 96-well plate, 12 x 8-well strips x 0.2 mL 3-99° C 4° C/sec ±0.1° C ±0.20°C at 55°C after 15 sec 
Analytik Jena Biometra TAdvanced 96 G 27.7 x 45.7 x 26.4 Touch screen 96 x 0.2 mL tubes, 96-well plate, 12 x 8-well strips x 0.2 mL 3-99° C 8° C/sec ±0.1° C ±0.20°C at 55°C after 15 sec 
QIAGEN QIAamplifier 96 26 x 43 x 21 7" color touch screen 96 x 0.2 mL tubes, 1 x 96-well plate, 12 x 8-well strips 4-99° C 3.33° C/sec ±0.1° C ±0.20°C at 55°C after 15 sec 
Edvotek EdvoCycler 2 - 7" HD color touch screen 48 x 0.2 mL tubes and 8-tube strips 4-99° C 4° C/sec - - 

*Dimensions are in cm. W x D x H