Mr. Cycle, Thermal Cycler

Description (Brief)
This object, affectionately referred to as “Mr. Cycle,” was the first prototype automated PCR machine or thermal cycler. Its robotic machinery is contained in a beige plastic housing. One side of the housing features a rainbow colored “California Dreamin’” sticker. It’s not known who applied the sticker to the prototype, but it may be a reference to the location of its creation or the “surfer dude” personality of the PCR process’s inventor.
The machinery consists of a liquid handling arm that slides up and down and a drawer portion. The drawer portion houses three blocks (from front to back): sample block, reagent block, and tip magazine. The sample block has four black hoses attached to it. The other ends of the hoses are attached to solenoid valves on the top of the machine. In operation, these solenoid valves would also have been attached to water baths via hoses. The water baths were not collected.
PCR, short for polymerase chain reaction, was a revolutionary laboratory technique developed by Kary Mullis at Cetus Corporation in 1983. PCR acts like a photocopier for genetic material, working on principals similar to nature’s own method for replicating DNA. With the reaction, scientists can take a single portion of DNA they wish to study and amplify it into millions of copies in only a few hours. This simple technique for creating large amounts of DNA resulted in huge leaps in genetic research in a variety of fields, from evolutionary biology to forensics to medicine.
Although the reaction is straightforward, requiring only a few chemicals, it is incredibly time-consuming to perform by hand. Because different steps of the reaction take place at different temperatures (hence the name “thermal cycling”), scientists performing the reaction were required to stand at the lab bench for several hours, moving the sample back and forth between water baths of different temperatures. While they loved the technique, scientists were eager for an automated machine that could perform the reaction for them.
Engineers at Cetus developed the “Mr. Cycle” prototype by modifying a Pro/pette (see object 1994.0031.01), an instrument that the company had previously created to be used for liquid handling. The tray on the front held the sample and could slide back and forth. When slid to the front, the sample tray would rest in a water bath. The black hoses brought water from baths of different temperatures (not pictured) as necessary. When slid to the back, the sample could be injected with new enzyme, a chemical used to speed up the reaction, that had to be added once during a cycle. These two features—water baths and the need to add enzyme during each cycle--would be phased out in all future prototypes (see object 1996.0166.02) and commercial models. The water baths were replaced first with Peltier devices for thermoelectric heating and cooling and later, in commercial models, with electric heating and refrigeration units. The enzyme problem was solved by isolating a heat-stable form from bacteria which live in geothermal hot springs. Previously, the enzyme had to be replaced in each cycle because it would degrade in the high-heat step of the reaction.
Currently not on view
Object Name
thermal cycler
date made
Physical Description
metal (overall material)
plastic (overall material)
rubber (overall material)
overall: 55.3 cm x 33 cm x 55.8 cm; 21 3/4 in x 13 in x 21 15/16 in
ID Number
accession number
catalog number
See more items in
Medicine and Science: Biological Sciences
Science & Mathematics
Biotechnology and Genetics
Polymerase Chain Reaction (PCR)
Data Source
National Museum of American History, Kenneth E. Behring Center


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