In December 1935, two Danish engineers, Borge Aagaard Nielsen and Carl Schroder, started a company in the old “Nyboder” quarter of Copenhagen, Denmark, to produce measuring equipment for the radio industry. These first instruments, or meters as they were called, gave the new company its name — Radiometer.
The E50101 was Radiometer’s first commercial blood gas analyzer.
The company enjoyed early success in telecommunications and soon found other opportunities for expansion. In 1937, it entered a cooperation with Carlsberg Laboratories in Copenhagen to develop an amplifier for use in measuring acidity in liquids. These first early “pH meters” became the basis for a new line of Radiometer electrochemistry products.
In the early 1950s, a worldwide polio epidemic took many lives despite the use of the Iron Lung. Dr. Poul Astrup, chief of the laboratory at the Epidemic Hospital in Copenhagen and anesthetist Bjorn Ibsen discovered that blood pH provided vital diagnostic information that could help save lives. This “Astrup Method” application for their pH meter interested Radiometer in the further study of the “acid-base status” of the blood. The result of their study was the inspiration for Radiometer’s new electromedical product line.
In 1954, Radiometer introduced the first commercial “blood gas apparatus,” the E50101. The new instrument immediately gained significant attention throughout the world. Virtually overnight, Radiometer became a world leader in blood gas instrumentation.
Accuracy, precision, and experience
The company’s glassworks products are manufactured by a group of experienced craftsmen and women who work quickly and accurately. A glass membrane with a diameter of approximately 18mm and a thickness of 8 – 10 hundredths of a millimeter is manufactured manually, with minimum technology by two craftsmen. Each membrane they make forms part of a pCO2 electrode, and the entire process takes less than two minutes.
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| Air is blown into the pipe until a bubble appears at the end. | Membrane is melted onto electrode tube. |
Thickness of membrane is checked with a dial gauge. |
Technicians sit next to a transportable furnace. On top of the furnace, there is a hole with a diameter of approximately 10cm. The bright light coming from this hole indicates a very high temperature (1475ÞC/2687ÞF) displayed by the digital thermometer. The glass workers sit close to the furnace facing a small mirror. To the right of the technicians is a work table with tools and a box of 14cm-long blowpipes with a diameter of less than 1cm. Wearing safety glasses, technicians use a pair of tongs to pick up the blowpipes. The blowpipe is placed into the furnace hole and dipped into a platinum crucible containing molten glass. It is then withdrawn from the furnace and turned a few times to distribute the heat. It is then put back into the hole and dipped into the molten glass again. After withdrawing the blowpipe from the furnace a second time, air is blown into the cold end of the pipe while turning it and examining it in the mirror. A bubble appears at the end of the pipe. After a few seconds the bubble is measured with a caliper gauge. The entire process takes 20 seconds.
The technician repeats this process, and within a few minutes about a dozen pipes with bubbles at the end are finished. The pipes are produced with impressive accuracy while maintaining a production time of 20 seconds per pipe. The color of the glass indicates whether its temperature is correct or not. It is all about being able to judge by eye, having experience and finding a work rhythm. Measurements are taken with a caliper gauge to make sure that the bubble (which is to be used as a membrane) has the exact measurement — down to a hundredth of a millimeter. Each Radiometer glass blower receives four-years of on-the-job training.
Glass lathe
The blowpipes are passed on to a person at the glass lathe. One at a time, the blowpipes are fixed to the lathe with the bubble facing outwards. A larger blowpipe is placed around the pipe, leaving a space of approximately 1cm between the two pipes all the way around. At the other end of the glass lathe a glass electrode tube with a diameter of approximately 3mm is attached. The outermost and larger pipe is heated with a flame. If the inside, smaller pipe is heated directly, it will crystallize and become useless. When the innermost blowpipe reaches the right temperature, the electrode tube at the other end of the lathe is slowly driven towards it. The electrode tube melts through the bubble in such a way that it cuts off a piece of the bubble. This piece of glass melts together with the electrode tube as a membrane at the end of the tube. It is important that the membrane has the right arch; otherwise, the arch can be altered by blowing air into the tube with a pedal. Next, the membrane is checked by looking at an enlargement of it on a screen. The entire process takes about one minute.
Newest multi profile blood gas analyzer ABL700 series.
Reference electrode
A new process is started to manufacture the reference electrode which uses two glass tubes with different diameters. One tube is equipped with a rubber hose at one end. The other tube, which is closed at one end, is held in the flame until it has reached a temperature at which it melts together with the first tube. The two tubes are joined, and while they melt together, they are rotated simultaneously while air is blown into the rubber hose. When the two tubes become one, a ceramic pin is melted into the tube. Subsequently, it is ground, beveled and cut to the correct measurement. The tube is sandblasted so it becomes frosted on one end, and then it is passed on to another department where it is equipped with a rod, cotton wool and an electrode. Finally, it is cast into a transparent plastic tube, and the reference electrode is ready.
Secret recipe
The glass workers make their work look easy, but technical skills and experience do not come overnight. Even those who might be able to pick up the glass workers’ skills quickly would have a difficult time duplicating their efforts. The glass in the platinum crucible in the furnace is made with Radiometer’s own secret recipe for the glass membrane.
Throughout Radiometer’s history, great advancements in technology have been successfully combined with old world craftsmanship to maintain the high standards demanded by today’s medical industry.
Katrin Malt Schwaab is with Radiometer in Copenhagen
