Fabrication and Characterization of Polymer‐Based Microchip Integrated with NH₄⁺‐ISFET Using a Small Diameter Wire as a Template of Channel

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

“…Channels of the polymer-based microfluidic chip were fabricated using polystyrene plates (ITEM 70128 500, Tamiya Co. Ltd., Japan) and stainless-steel wires (SUS304-W1, Waki Industrial Co. Ltd., Japan) according to almost the same method. 41,[53][54][55] The chip design of a polymer-based microfluidic chip detector with an embedded NO3 --ISE and a Na + -ISE as a reference electrode was similar to that shown in a previous paper. [53][54][55] However, the ISE embedded in the chip was improved to a cartridge-type ISE.…”

“…41,[53][54][55] The chip design of a polymer-based microfluidic chip detector with an embedded NO3 --ISE and a Na + -ISE as a reference electrode was similar to that shown in a previous paper. [53][54][55] However, the ISE embedded in the chip was improved to a cartridge-type ISE. The cartridge-type ISE can be easily replaced by a new ISE, in the case that the ISE shows a lower performance during long-term use.…”

“…We have already developed microfluidic chips integrated with ISFETs fabricated on polystyrene plates by using stainless-steel wire as a template for the channel, for the determination of ammonium ion and ionic surfactants. [53][54][55] In this case, we used an Ag/AgCl wire electrode as a reference electrode in the polymer-based microfluidic chip, and carrier solutions containing 1.0 × 10 -2 M chloride ion were also used for the determination of a baseline potential. The Ag/AgCl wire electrode responds to the chloride ion in the carrier solution.…”

A New Microfluidic Polymer Chip with an Embedded Cationic Surfactant Ion-selective Optode as a Detector for the Determination of Cationic Surfactants

“…This is because ISE and ISFET are easy to miniaturize and can easily be fabricated at low cost, and the sensitivity of ISE and ISFET does not decrease, even if their size is reduced. [10][11][12][13][14][15][16][17] We have already developed a new microfluidic polymer chip with an embedded ISE, where a channel on the chip was prepared by using a small-diameter wire as a template of the channel. 11,12,[14][15][16][17] On the other hand, ion-selective optical sensor (Optode) membranes are suited for a detector of microfluidic chips, compared with the ISE and the ISFET.…”

“…[7][8][9][10][11][12][13][14][15][16][17] Among electrochemical detection methods, an ion-selective electrode (ISE) and an ion-sensitive field effect transistor (ISFET) are effective as detection methods of a microfluidic chip. This is because ISE and ISFET are easy to miniaturize and can easily be fabricated at low cost, and the sensitivity of ISE and ISFET does not decrease, even if their size is reduced.…”