An integrated module for sensing pO2, pCO2, and pH

Abstract An integrated sensing module for monitoring pO 2 , pCO 2 , and pH was fabricated. Electrode patterns were formed on a glass substrate and the containers for corresponding electrolyte solutions were formed by anisotropically etching a silicon substrate. The Clark-type oxygen electrode and the Severinghaus-type pCO 2 electrode were used for sensing pO 2 and pCO 2 , respectively. An iridium oxide indicator electrode was used for the sensing element of the pCO 2 electrode and the pH electrode. The pH electrode was a combination electrode with an on-chip liquid-junction reference electrode. Distinct responses were observed for each of these electrodes. The linear relationships between the output current of the oxygen electrode and pO 2 , and between the potential of the carbon dioxide electrode and logarithm of pCO 2 were confirmed. The output potential of the pH electrode was compared using the on-chip liquid-junction reference electrode and a macroscopic commercial reference electrode. No substantial difference was observed. Simultaneous operation of the three electrodes was confirmed.

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