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Understanding The History and Development
of the PELCO® Microwave Tissue Processors,
and thus the Published Results of
Researchers Using These Instruments


This page is written to provide a framework for the researcher/clinical technician to understand, to give some context to the published material where a Microwave Tissue Processor made by Ted Pella, Inc. (prefixed with the brand name PELCO®) was used as part of the experimental or clinical published results. The first PELCO® Microwave Tissue Processor produced by Ted Pella, Inc. came out in 1995. It was created primary for speeding up preparation times for sample preparation (all steps, fixation through polymerization as well as specialized staining and antibody work) for Transmission Electron Microscopy. It quickly evolved into a unit that could do decalcification for both EM and LM; histological sample preparation (fixation through paraffin embedding and stains, and primary/secondary antibody work) and fluorescence microscopy sample preparation. It was used for plant and animal and bacterial samples.

The person leading the development of the various Microwave Tissue Processors was Rick Giberson of Ted Pella, Inc. Rick headed up the research and development of this ongoing project for 21 years. Rick collaborated with many researchers and technicians over the years, who tried out the instruments and gave Rick valuable feedback. Some of them also partnered with Rick on producing published research. Some of these people included Mark Sanders from the Univ. of Minnesota, Dr. Richard Demaree and Dr. Jonathan Day from Cal State University Chico, Dr. Robert Cardiff and Dr. Jose Galvez and Grete Adamson and Pat Kysar of University of California Davis, Dr. Charles Meshul and Cindy Moore of Oregon Science and Health University, Dr. Douglas Keene of Shriners Hospital in Portland, OR, Dr. Richard Webb of the University of Queensland, and Dr. Kent McDonald of the University of California Berkeley. Rick worked with hundreds of researchers over the years.

Rick and other researchers pushed the boundaries of what microwave tissue processing could do. They tested times, wattages, water loads and flows, different steps and all sorts of permutations of reagents and reagent concentrations and times related to those steps. All sorts of accessories were developed to facilitate the processing of different types of tissue through various steps.

It was the early success of our customers that drove us to continue developing the technology.

Following is a brief historical timeline of microwave models and key accessories, the capabilities they had and what could be done with them.

PELCO 3400. This was the first microwave, which had a laboratory exhaust to allow processing with EM reagents.

PELCO 3420. This was an optional Load Cooler accessory, which introduced the feature of being able to cool a water load in the microwave cavity.

PELCO 3430. This was a optional accessory Variable Wattage Controller. Allowing for six settings, this was the first time that controlled, constant “on” wattage could itself be incorporated into processing steps.

PELCO 3440 (“MAX”). This was a 3400 microwave that included the accessories for temperature control and plumbing for load cooling and digital temperature monitoring.

PELCO 3450. This was a 3440 microwave with a 3420 Load Cooler.

PELCO 3451. The 3451 was the peak of the design before the 34700. It had all the elements necessary and could support the PELCO ColdSpot; but it was not programmable.

PELCO ColdSpot®. Prior to the ColdSpot, a microwave had to be calibrated with a neon bulb array to find the “hotspot” and “cooler spots” to know where in the oven cavity to place a sample or a water load. Earlier papers sometimes discuss this.

The PELCO Coldspot® was invented not long before the PELCO BioWave® 34700. It used patented technology (US Patent #6329645) to provide a processing surface with a controllable, even-across the surface temperature during microwave processing. When paired with a load cooler (available separately with several units prior to the PELCO BioWave® 34700 and incorporated into that and all successive units), this provided repeatable results, and got away from “hotspots and coldspots”.

PELCO 3470: Nicknamed the “Hornet”, it was the first PELCO® microwave that had a built-in microprocessor control module. It was short-lived.

PELCO BioWave® 34700. This unit was released in the year 2000. This was the first model that used the newly registered trademarked name PELCO BioWave®.

This unit was a complete redesign and represented a whole new direction for PELCO® microwave processors. With this unit all functionality was enclosed in a single case, along with the controls (which were analog). The big change, however, was the incorporation of a newly patented invention, the PELCO Coldspot®. This created a watercooled surface inside the microwave cavity which presented a hotspot-free, uniform temperature processing surface. As a whole, the BioWave with the Coldspot was the first microwave tissue processor that allowed for quality, reproducible results which matched or exceeded the quality of equivalent processing on the bench.

This unit also incorporated the ability to control the application of microwave power as “always on” or “always off”, as opposed to all other microwave tissue processors which apply microwave power in timed, programmed “on/off” bursts that would stop delivering microwave power entirely when a certain “high temperature” was reached. The PELCO BioWave® 34700 allowed for a constant, lower temperature to be maintained which did not “cook” tissue, and a controlled microwave application. This yielded repeatable results for the first time in microwave tissue processing.

Papers and studies done with units prior to this were more limited in what they were able to accomplish. Starting with the 34700, a whole new ability to control time and temperature in the microwave cavity was introduced. Published results using this unit and those afterwards incorporate additional capabilities which were difficult, and sometimes impossible to achieve.

The following year, Rick Giberson and Dr. Richard Demaree published the book “Microwave Techniques and Protocols”. This summarized the work of a number researchers and technicians up to this time.

PELCO BioWave® DFR-10 34800. This unit was released in 2002. The DFR-10 introduced a specialized functionality devoted to rapid decalcification and formalin fixation. With this unit came the PELCO SteadyTemp™, a chiller with custom parameters specifically tuned to work with the PELCO BioWave®. This incorporated a temperature controlled recirculating bath which could be used for two purposes:

  1. For either formalin fixation, for 1-hour histological fixation of up to 2mm thick tissue (a patent was granted around this technology, US Patent #6875583), or

  2. For EDTA for decalcification of bone, reducing decalcification by up to a 5-10x time reduction over typical bench EDTA decalcification. A patent was granted around this technology (US Patent #6797928).

Also in coordination with the release of this unit, a patent was granted.

This unit also introduced the capability for running up to 96 straight hours.

While this unit itself is not available today, the various accessories still are and the same functionality can be accomplished today.

PELCO BioWave® Pro 36500. This unit was released in 2007. It got away from analog controls, introducing the use of touchscreen technology and increased the ability to store protocols.

PELCO BioWave® Pro+ 36700. This unit was introduced in 2016. It provide a much updated and upgraded touchscreen, It also created a faster, easier way to upload and download protocols, and increased the number of protocols that could be stored. It included better storage of protocol settings for clinical documentation.