A single-chip pH sensor fabricated by a conventional CMOS process
SENSORS, 2002 IEEE - Tập 1 - Trang 350-355 vol.1
Tóm tắt
A pH sensor fabricated on a single chip by an unmodified commercial CMOS process is described The sensor comprises a circuit for making differential measurements between ISFET and REFET both biased by the same reference electrode. The ISFET has a floating electrode structure and uses the silicon nitride passivation layer as the pH sensitive material. It is found to have a large threshold voltage caused by charge trapped on the floating electrode. A large reference electrode voltage is therefore required to bias the ISFET, this is shown to cause the operating point to drift. However the threshold voltage has been successfully reduced by exposure to UV radiation. The REFET is formed by deposition of a PVC membrane onto an ISFET and the reference electrode is simply a metal contact. The complete circuit provides an output voltage proportional to pH and operates from a single 5V supply.
Từ khóa
#CMOS process #Electrodes #FETs #Circuits #Semiconductor device measurement #Silicon #Threshold voltage #Biosensors #Dielectrics and electrical insulation #HydrogenTài liệu tham khảo
10.1109/55.20408
10.1016/S0925-4005(01)00639-6
10.1016/0250-6874(89)87038-6
10.1109/16.737468
10.1016/S0003-2670(00)82761-0
10.1016/S0925-4005(99)00135-5
errachid, 1999, A simple REFET for pH detection in differential mode Sensors and Actuators B, 60
10.1016/0250-6874(81)80004-2
10.1109/TBME.1986.325881
10.1109/IEDM.1988.32899
10.1016/0250-6874(85)87010-4
10.1109/T-ED.1987.23140