title: 5×5 CMOS capacitive sensor array for detection of the neurotransmitter dopamine.
abstract: This work presents miniaturized CMOS (complementary metal oxide semiconductor) capacitive sensors for detection of the neurotransmitter dopamine (DA) down to the sub-fM range. Sensing resolution is significantly enhanced by monolithic sensor integration to reduce the parasitic effect and the use of sub-μm interdigitated microelectrodes as the sensing interface. The 5 × 5 sensor array contains five designs of different electrode sizes and each design has five sensors. The positive charges produced from protonation of boronate and amino group after immobilization of 4-carboxyphenylboronic acid (CPBA) result in an increase of the electrode-analyte capacitance. Then the negative charges produced after binding of CPBA and DA molecules decrease the electrode-analyte capacitance. Signal transduction is achieved through a CMOS readout circuit whose output frequency is inversely proportional to the capacitance. Experimental results showed the ratios of average percentage capacitance changes of the experiment groups over those of the control groups were all larger than one for the five designs at DA concentration of 0.1 fM. Selectivity against the non-analyte species, such as tyramine, has also been demonstrated.
authors.affiliation: Department of Electrical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, ROC. sclu@ee.nthu.edu.tw
authors.forename: Michael S-C
authors.initials: MS
authors.lastname: Lu
authors.forename: Yi-Chung
authors.initials: YC
authors.lastname: Chen
authors.forename: Po-Chiun
authors.initials: PC
authors.lastname: Huang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D001897:Boronic Acids; D004298:Dopamine / Q000032:analysis*; D025802:Electric Capacitance; D004582:Electronics, Medical / Q000295:instrumentation; D004867:Equipment Design; D008839:Microelectrodes; D018377:Neurotransmitter Agents / Q000032:analysis*; D012666:Semiconductors; D012822:Silicon Dioxide
chemical_list: D001897:Boronic Acids; D018377:Neurotransmitter Agents; D012822:Silicon Dioxide; D004298:Dopamine