Ion Sensitive FET (ISFET) - What and Why?. Indicator electrode: ISEs. Ion selective electrodes (ISEs) Fritz Haber discovered (1901) that there is a change in potential across a glass membrane when its two sides are in solutions of different acidity.
- What and Why?
which contains the analyte at an activity
of (aA)sample, from an internal solution
containing the analyte with an activity
potential of the two reference electrodes
are constant, any change in Ecellis a result
of a change in the membrane’s potential.
Ecell = Eref(int) − Eref(sample)+ Emem + Ej
pH = 7.4 is regulated very accurately by the body. If the pH of the blood
gets outside the range 7.35 to 7.45 the results can be fatal.
not affected by the
presence of oxidizing or
(CO(NH2)2) to produce NH3 (ammonia)
2NH4+(aq) + CO32−(aq)
ISFET small & reliable for in-vivo biosensing applications
Conventional ISE too big, fragile & unstable for in-vivo biosensing applications