A capacitive field-effect sensor for the direct determination of organophosphorus pesticides

Schöning, Michael J.; Arzdorf, Michael; Mulchandani, Priti; Chen, W.; Mulchandani, Ashok

doi:10.1016/s0925-4005(03)00071-6

Cited by 40 publications

(20 citation statements)

References 13 publications

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“…It can be seen that the voltage shift has a linear relation with pH values between 3 and 9, and the per pH voltage shift can be extracted from the plot to be 46.5 mV/pH. This voltage shift closely follows the literature values for an Al 2 O 3 surface on nanowire sensors [13,14]. Fig.…”

Section: IIIsupporting

confidence: 81%

Low-cost top-down zinc oxide nanowire sensors through a highly transferable ion beam etching for healthcare applications

Zeimpekis

Ditshego

et al. 2016

Microelectronic Engineering

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Abstract-In this work, we demonstrate a wafer-level zinc oxide (ZnO) nanowire fabrication process using ion beam etching and a spacer etch technique. The proposed process can accurately define nanowires without an advanced photolithography and provide a high yield over a 6-inch wafer. The fabricated nanowires are 36 nm wide and 86 nm thick and present excellent transistor characteristics. The pH sensitivity using a liquid gate was found to be 46.5 mV/pH, while the pH sensitivity using a bottom gate showed a sensitivity of 366 mV/pH, which is attributed to the capacitance coupling between the top-and bottom-gates. The maximum process temperature used in the fabrication of the nanowire sensors is optimized to be 200°C (after wet oxidation) which makes it applicable to low-cost substrates such as glass and plastic. The Ion Beam Etching (IBE) process in this work is shown to be highly transferable and can therefore be directly used to form nanowires of different materials, such as polysilicon and molybdenum disulfide, by only an adjustment of the etch time.

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Section: IIIsupporting

confidence: 81%

Low-cost top-down zinc oxide nanowire sensors through a highly transferable ion beam etching for healthcare applications

Zeimpekis

Ditshego

et al. 2016

Microelectronic Engineering

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“…As already discussed in [11], the pH behaviour of the three investigated pH-sensing transducer materials Al 2 O 3 , Ta 2 O 5 and Si 3 N 4 show results which are in a good agreement with values found in literature. There is, however, a slight decrease in the original pH sensitivity on modification of the surface by OPH.…”

Section: Resultssupporting

confidence: 90%

“…The lower detection limit (i.e., three times the standard deviation of the response obtained for a blank signal) of the presented silicon-based enzyme biosensor is 2 µM. The sensitivities towards paraoxon are similar for all three types of pH-sensitive transducer materials investigated so far [11]. The presented capacitive field-effect biosensors do not reach the nanomolar detection limit of AChE-based enzyme biosensors, but have a much faster response characteristic without any complicated measurement and renewal protocol.…”

Section: Resultsmentioning

confidence: 73%

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Towards a Capacitive Enzyme Sensor for Direct Determination of Organophosphorus Pesticides: Fundamental Studies and Aspects of Development

Schöning

Arzdorf

Mulchandani

et al. 2003

Sensors

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Abstract:The realisation of a miniaturised potentiometric enzyme biosensor is presented. The biosensor chip utilises the enzyme organophosphorus hydrolase (OPH) for the direct determination of pesticides. The transducer structure of the sensor chip consists of a pHsensitive capacitive electrolyte-insulator-semiconductor (EIS) structure that reacts towards pH changes caused by the OPH-catalysed hydrolysis of the organophosphate compounds. The biosensor is operated versus a conventional Ag/AgCl reference electrode. Measurements were performed in the capacitance/voltage (C/V) and constant capacitance (ConCap) mode for the two different pesticides paraoxon and parathion. For the development of this new type of biosensor, different immobilisation strategies, influence of buffer composition and concentration, transducer material, detection limit, long-term stability and selectivity have been studied.

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“…An optical transducer to monitor the chromophoric products [4,5] and an amperometric transducer to monitor the oxidation or reduction current of the hydrolysis products [6,7] have been reported. However, simple and practical potentiometric biosensors integrating OPH with pH sensors such as glass pH electrodes [8], pH sensitive field-effect transistors [9], or capacitive electrolyte-insular-silicon (EIS) field-effect transducers [10] were the most important ones because protons are the common product of OPs hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

Model of a pH‐Based Potentiometric Biosensor Immobilizing Organophosphorus Hydrolase

et al. 2006

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A model for predicting the steady-state response of a pH-based potentiometric biosensor immobilizing organophosphorus hydrolase (OPH) is developed. The model combines the processes of diffusion and enzymatic reaction in the membrane. Key factors influencing the system response, such as enzyme reaction order, Thiele modulus, and buffer concentration are discussed in detail. It is possible to obtain a good linear response by designing an enzyme electrode with a high enough Thiele modulus and by appropriately controlling added buffer concentrations. It is found that the model is in reasonable agreement with the experiment results.

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A capacitive field-effect sensor for the direct determination of organophosphorus pesticides

Cited by 40 publications

References 13 publications

Low-cost top-down zinc oxide nanowire sensors through a highly transferable ion beam etching for healthcare applications

Low-cost top-down zinc oxide nanowire sensors through a highly transferable ion beam etching for healthcare applications

Towards a Capacitive Enzyme Sensor for Direct Determination of Organophosphorus Pesticides: Fundamental Studies and Aspects of Development

Model of a pH‐Based Potentiometric Biosensor Immobilizing Organophosphorus Hydrolase

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