Microfabrication of screen-printed nanoliter vials with embedded surface-modified electrodes

Abstract

A self-contained ion-selective sensing system within a nanoliter-volume vial has been developed by integrating screen printing, laser ablation, and molecular imprinting techniques. Screen printing and laser ablation are used in tandem to fabricate nanoliter-volume vials with carbon and Ag/AgCl ring electrodes embedded in the sidewalls. Using multisweep cyclic voltammetry, the surface of the carbon electrode can be modified with a polypyrrole film. By polymerizing pyrrole in the presence of nitrate, pores complementary to the nitrate anion in size, shape, and charge distribution are formed in the resulting film. Electrochemical cells modified with this nitrate-imprinted polypyrrole film show a near-Nernstian response to nitrate, and excellent reproducibility. The integration of molecular recognition and electrochemical response in the nanoliter vials is demonstrated by the detection of as little as 0.36 ng nitrate in nanoliter-volume samples. The integration of tailored molecular recognition within nanoliter vials via established fabrication and imprinting protocols should result in a number of nanosensor devices with applications in BioMEMS and micro total analysis systems.

Microfluidic Polymer Chip with an Embedded Ion-Selective Electrode Detector for Nitrate-Ion Assay in Environmental Samples

“…The lower detection limit of the present microfluidic chip for nitrate ion is superior to that of other microfluidic chips. 29,30 The level of nitrate ion in environmental water samples, such as a tap water, well-water and water for agricultural use was determined by the developed microfluidic chip with the embedded NO3 --ISE. …”

“…1.6 × 10 -5 M). Bachas et al 30 reported on the microfabrication of screenprinted nanoliter vials with embedded surface-modified electrodes and its application to μ-TAS for the potentiometric determination of nitrate ion. However, the NO3 --ISE showed a slope of -45.4 ± 0.9 mV/decade for the nitrate ion, and the detection limit was 4 × 10 -4 M for the nitrate ion.…”

Molecularly imprinted polypyrrole films: Some key parameters for electrochemical picomolar detection of dopamine

“…Indeed, electrochemistry has received much attention as a means of preparing molecularly imprinted polypyrrole (PPy) [8,9,13,38] and developing high performance electrochemical sensors [8][9][10]. The reasons for choosing PPy films are the following: PPy can be straightforwardly prepared by in situ electropolymerization at the electrode surface in either the presence or absence of dopamine; film formation of PPy is fast; PPy is well known to be partially crosslinked [39], so that a crosslinking comonomer is not necessary to be used; extraction and rebinding of the template can be performed electrochemically.…”

Sequential Injection Analysis of Thiocyanate Ions Using a Microfluidic Polymer Chip with an Embedded Ion-Selective Electrode

“…Microfluidic chip technologies [12][13][14][15][16][17][18][19][20][21] have attracted much attention because of lower consumption of reagents and smaller sample volumes. However, the detection systems for the microfluidic chips still remain large in size, compared with the chips themselves.…”

“…However, only a few studies regarding microfluidic chips with embedded miniaturized ISEs have been reported. [15][16][17][18][19][20][21] We have already developed a new microfluidic polymer chip with an embedded NO3 --ISE and a Na + -ISE as a reference electrode, where a channel on the chip was prepared by using a small-diameter wire as a template of the channel. 21 Recently, sequential injection analysis (SIA) has been recognized as an effective technique to satisfy the requirement of routine water analysis because SIA offers the advantages of automatic operation, high sample throughput and low consumption of a reagent.…”