The circuitry forms part of testing apparatus for measuring the concentration of ions in fluids, primarily body fluids, including the measurement of chlorides, ionized calcium, sodium and potassium as well as other ions. A small sample fluid is subjected to a controlled mechanical oscillation to thoroughly...http://www.google.de/patents/US4460967?utm_source=gb-gplus-sharePatent US4460967 - Electronic circuit for measuring and displaying ion concentration in fluid
