LTCC-based microchips for the electrochemical detection of phenolic compounds

The low temperature co-fired ceramic (LTCC) technology can be defined as the fabrication of multilayer applications with the aid of single tapes, which are to be used to integrate passive elements like resistors, capacitors and inductors into the substrate. Using modern manufacturing processes, a large-scale cost-effective production is possible. The ceramic is chemical inert with a good thermal conductivity and just cause excellent properties for the development of “lab-on-a-chip” systems. These devices are described as small, portable and large-scale analytical tools, which includes a number of steps for an automatic analysis. Such systems are typically manufactured out of silicon, glass or polymers. However, devices made from silicon or glass are relatively expensive. Polymers allow low production costs but surface properties of materials are often crucial. A promising alternative seems to be the here presented LTCC-technique. The aim of this study is the development of a “lab-on-a-chip” device based on a LTCC multilayer chip including integrated sample preparation, capillary electrophoresis and electrochemical detection (ECD) as well as all required electrodes and contacts. The separation and detection of numerous phenolic compounds were investigated. Samples were injected by an electrokinetic method and were detected amperometrically. Detection limits were found to be between 12.5 and 250 μmol. The migration velocity was found to be between 0.018 and 0.038 cm s−1 applying a field strength of 86.5 V cm−1. A polyphenol mixture of dopamine, pyrogallol and gallic acid could be separated and detected amperometrically on LTCC-microchips.