Centrifugal Microfluidics with Integrated Sensing Microdome Optodes for Multiion Detection

Abstract

An array of four sensing microdome optodes (potassium, sodium, calcium, and chloride) was incorporated into a centrifugal microfluidics platform to obtain a multiion analysis system. The behavior of each sensing microdome was in good agreement with a theoretical model describing the response. The selectivity of each optode over common interfering ions was established and was used to identify calibrant solutions that can be employed for the simultaneous calibration of all four optodes without significant cross-interference. The microfluidic platform was designed to facilitate both three-point calibration of the optodes and triplicate analysis of a sample within a single run, which increases the accuracy of the determination. The optimized microfluidic system was used to determine simultaneously the concentration of potassium, sodium, calcium, and chloride in aquarium water (with the composition of Lake Tanganyika water) with less than 6% error. The simple process of fabrication of these microdomes and their incorporation into a centrifugal microfluidic platform should facilitate the development of portable ion-sensing analysis systems.

Theory, fabrication and applications of microfluidic and nanofluidic biosensors

“…In addition, detection methods could also rely on mechanical changes induced owing to adsorption of target molecules or analytes to cantilevers [35][36][37] or nanowires [33], changes to inherent biomolecular charge in the case of field-effect transistors, sometimes also classified as microarray-type biosensors [38][39][40][41][42][43], or electrochemical changes such as those arising from redox reactions inducing variations in current flow [44,45]. Therefore, biosensors form a complex area of research given the diversity of target molecules, need for low false positives and variety of detection platforms available [46][47][48][49][50] with a brief summary presented in table 1a.…”

Invited Review Article: Review of centrifugal microfluidic and bio-optical disks

“…67 The biodisks can be used as ionic biosensors. 68 The disks also lend themselves to fundamental studies of microfluidics, such as imaging of menisci under noninertial forces. 69 Bioassays are a clear application for biodisks.…”

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

“…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. [18][19][20][21][22][23][24] From the viewpoints of applications to microfluidic technology, optodes are superior to ISEs because they are not subject to electrical noise, and no contacts to microfluidic chips are required for measurements. Furthermore, no reference electrode is needed for measurements using optodes.…”

“…[20][21][22][23][24] Flow-injection analysis (FIA) is one of the analytical methods utilizing a flow system originated by Ruzicka et al In the FIA, after a sample solution is injected into a carrier solution, continuously flowed by a pump and mixed with a reagent solution, a target component in the sample is quantified by a peak signal obtained by a downstream detector. The FIA has attracted much attention as a rapid analytical method capable of precisely controlling the mixing and reaction between a reagent solution and a sample solution in a flow system.…”