Electrochemical Sensing on Microfluidic Chips

Alberto Escarpa, Marla Cristina Gonzalez and Miguel A. Lopez Departamento de Qulmica Analltica, Qulmica Flsica e Ingenierla Qulmica, Universidad de Alcala, Ctra, Madrid-Barcelona km 33,600,28871, Alcala de Henares, Madrid, Spain 

The final objective of analytical miniaturized systems is represented by the concept of micro total analysis systems (micro-TASs) and lab-on-a-chip (LOC) technology [1, 2], Micro-TAS concept was developed from the modification of the total analysis systems (TASs) by downsizing and integrating its analytical multiple steps (sample preparation, separa-tion/reaction, and detection) onto single monolithic devices. The immediate consequence of this miniaturization in scale is that these devices allow fast analysis time and extremely low samples and reagents consumption. 

However, one of the most relevant characteristics of these analytical microsystems is the possibility of handling fluidics on the nanoliter and even picoliter scale, which has widened the scope of micro-TAS to microfluidics, defined as the science and technology of systems that process or manipulate small amounts of fluidics (10 -10 1), using channels measuring from tens to hundreds of micrometers [1]. 

An important product of microfluidic-LOC technology is the termed microfluidic chip (MC). An MC is an analytical system constituted at least by an injector (where a sample plug is loaded), a set of microchannels (where hydrodynamic or electrophoretic trans-port/separation of analytes is performed) interfaced suitably to reservoirs (where different solutions/samples are deposited) and a detector (where molecule detection is carried out). Microchannels and reservoirs are fabricated using microfabrication techniques and facilities (i.e., photolithography or micromolding) to form channels for sample injection. 

Edited by Alberto Escarpa, Marfa Cristina Gonzdlez and Miguel Angel Ldpez. 2015 John Wiley Sons, Ltd. Published 2015 by John Wiley Sons, Ltd. 

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Micro-TAS, lab-on-a-chip devices or microfluidics in Analytical Chemistry can be seen as different analytical microsystems comprising (1) the direct measurement of one or a few components with little or no sample preparation (p-sensors) (2) the measurement of one or a few components which require some treatment of the sample (pFlA) (3) the analysis of more complex samples involving the separation of their components (p-HPLC and p-CE). In all cases, one of the oldest and most important challenges in analytical chemistry is chased the accurate measurement of a specific compound in a complex matrix. Taking in consideration these principles, the aim of this chapter would be mainly focus on the integration of sensors or sensor-like systems in microfluidic systems as platforms for electrochemical sensing in the environmental field. 

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