Chapter 26 Thick- and thin-film DNA sensors

The use of thick- and thin film electrodes as supports for genosensor devices offers enormous opportunities for their application in molecular diagnosis. The technologies used in the fabrication of both thick- and thin-film electrodes allow the mass production of reproducible, inexpensive and mechanically robust strip solid electrodes. Other important advantages of these electrodes are the possibility of miniaturization as well as their ease of manipulation in a disposable manner and therefore the use of small volumes. To detect transcriptional profiling and single nucleotide polymorphism thin-film arrays of 14, 20, 25, 48, and 64 electrodes have been fabricated, using lithographic techniques. Readout systems for these arrays based on electrical detection have also been developed. Moreover, a thick-film sensor array suitable for automation combined to readout based on intermittent pulse amperometry (IPA) has been commercialized. These genosensors and the readout instruments provide a simple, accurate and inexpensive platform for patient diagnosis. It is more than probable that arrays for 50–100 DNA sequences will be needed for some clinical applications. Although it is not difficult to design electrode pads with reproducible dimensions of a micron or less, the electrochemical readout requires mechanical connections to each individual electrode.