Clark, Leland

An example of amperometric methods used for analytical purposes is the sensor proposed in 1953 by Leland C. Clark, Jr. for determining the concentration of dissolved molecular oxygen in aqueous solutions (chiefly biological fluids). A schematic of the sensor is shown in Fig. 23.1. A cylindrical cap (1) houses the platinum or other indicator electrode (2), the cylindrical auxiliary electrode (3), and an electrolyte (e.g., KCl) solution (4). The internal solution is separated by the polymer... 

Submitted by Gerald J. Cox and Harrtette King. Checked by H. T. Clarke and Jessica P. Leland. 

Helen K. Berry Otto A. Bessey Ludwig W. Blau Oscar Bodansky William Duane Brown Helen B. Burch Leland C. Clark Konrad Dobriner Harry J. Deuel, Jr. 

Leland C. Clark, Jr., Elizabeth Beck, and Haskell Thompson, J. Clin. Endocrinol., 11, 8490 (1951). 

John R. Murlin, Leslie E. Edwards, Estelle E. Hawley, and Leland C. Clark, J. Nutrition, 31, 533554 (1946). 

Clark oxygen electrode. [D. t. Sawyer, A. Sobkowiak, and J. L. Roberts, Jr., Electrochemistry for Chemists, 2nd eel. (New York Wiley. 1995).] A modern, commercial oxygen electrode is a three-electrode design with a Au cathode, a Ag anode, a Ag I AgBr reference electrode, and a 50-(im-thick fluorinated ethylene-propylene polymer membrane. Leland Clark, who invented the Clark oxygen electrode, also invented the glucose monitor and the heart-lung machine. 

In the mid-1950s, Leland Clark developed an electrochemical method for oxygen measurements in biological fluids and made the discovery that if the Pt electrode used for detection could be separated from the biological medium by a gas permeable... 

Leland C. Clark Jr. (1918-2005) presented his first paper about the oxygen electrode, later named the Clark electrode, on 15 April 1956, at a meeting of the American Society for Artificial Organs during the annual meetings of the Federated Societies for Experimental Biology [96]. 

Ferdinand Rodriguez, Leland M. Vane, John J. Schlueter, and Peter Clark... 

An early reference to the concept of a biosensor is from Dr. Leland C. Clark, who worked on biosensors in the early 1960s (2) developing an enzyme electrode for glucose concentration measurement with the enzyme glucose oxidase, a measurement that is important in the diagnosis and treatment of disorders of carbohydrate metabolism in diabetes patients. Still today, the most common biosensors used are for glucose analysis. 

In 1954 Leland Clark demonstrated that a platinum cathode would measure the oxygen concentration of blood when it and a reference electrode were covered by an oxygen permeable membrane. Later in that same year Stow and Severinghaus showed that carbon dioxide could be estimated in blood with a glass electrode fitted with a gas permeable membrane. In the seventies the Huchs demonstrated that mechanical adaptations of these devices could be utilized to provide transcutaneous (non-invasive) measurement of arterial blood gas concentration if the skin area surrounding the sensor was heated to 44 - 45°C. 

As previously discussed, perfluoro [15]crown-5 has great potential as a NMR imaging agent (4J. This crown ether has only one fluorine resonance making very sharp pictures during brain scans and spinal scans of animals possible. Perfluoro [15]crown-5 is also used successfully as an oxygen carrier in collaborative studies between our group and Dr. Leland Clark s laboratory. Work at Air Products has established that the perfluoro crown ethers are nontoxic in animals and are therefore very different from hydrocarbon crown ethers. 

Leland C. Clark developed this well-known oxygen sensor in 1956 which is widely used for physiological, industrial, and environmental analysis. It is an amperomet-ric sensor which consists of a working electrode, a reference electrode, and the electrolyte as shown in Fig. 3.1. 

---