Abstract: A blood pH measurement device comprises a tube through which blood or other ion-containing fluid flows, at least one dry reference electrode, a proton diffusion differentiator, an ion-sensitive field-effect transistor, and a pH meter. The tube can comprise an annular wall with an entry, an exit, and a sensor floor. The dry reference electrode is preferably located within the tube between the entry and the exit and opposite the sensor floor. It is also contemplated that the dry reference electrode is surrounded by a membrane and is, at least partially, associated with the interior surface of the annular wall. The contemplated invention can also include a proton diffusion differentiator, such as an electrolyte separation layer, connecting the external surface of the sensor floor to an ion-selective field effect transistor (ISFET), wherein the ISFET measures the ion concentration of the blood.

Abstract: A meter is adapted for measuring concentrations of a chemical in a flowing solution. The meter has a barrier that shields a sensor from the high turbulence of the solution flow. One or more membranes can be employed to selectively filter out various ions or other chemicals.

Abstract: A meter is adapted for measuring concentrations of a chemical in a flowing solution. The meter has a barrier that shields a sensor from the high turbulence of the solution flow. One or more membranes can be employed to selectively filter out various ions or other chemicals.

Abstract: A meter is adapted for measuring concentrations of a chemical in a flowing solution. The meter has a barrier that shields a sensor from the high turbulence of the solution flow. One or more membranes can be employed to selectively filter out various ions or other chemicals.

Abstract: An ion meter is calibrated by providing two ISFETS with different areas, where the two gate areas are used to calibrate the two ISFETS with respect to one another. The use of two ISFET gates that can be calibrated with respect to one another eliminates the need for an ion meter to be recalibrated before every use, and allows the ion meter to measure the concentration in the solution over an extended period of time.