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Biomedical Optics & Medical Imaging

thin-film sensors improve molecular biomarker detection

From oemagazine June/July, 2005. astrobiology
31 January 2005, SPIE Newsroom. DOI: xx.xxxx

This computer-generated photograph depicts the format of the biomimetic sensor array.

Cranfield University

Biomimetic molecular sensor arrays based on artificial molecular receptors are of great interest to the field of astrobiology for the in situ detection of molecules indicative of present or past life (biomarkers). In a joint collaboration, researchers at Cranfield University (Silsoe, UK) and the University of Leicester (Leicester, UK) fabricated 5.1-nm-thick molecular imprinted polymer (MIP) thin films on gold surfaces suitable for optical sensing and electrical measurements. "MIP receptors are integrated and immobilized onto individual sensors of the array via ink-jet printing and in situ photo-initiated radical polymerization," says Olivier Henry of the research team.

The micro-fabricated sensor array consists of both optical and electrical transducers. The optical transducers are based on surface plasmon resonance, which is sensitive to refractive index changes, while the electrochemical transducers use impedimetric measurements performed with interdigitated electrodes. The group fabricated both sensor types using standard silicon-based micro-fabrication techniques, enabling a smaller size and lower-mass and power-consumption package. "Many issues have to be addressed, but this technique should be easy to use, and the operation should be remotely controlled," says Henry.

The sensor array is being designed to solve some of the most problematic disadvantages in the natural or derivatized bio-receptors used in conventional sensors—for example, lack of robustness and specificity under harsh working conditions. "Using MIP technology allows us to design very robust and very specific recognition elements for almost any kind of molecules. These kinds of 'smart-plastics' can be reused under the same harsh conditions," says Henry. Future work will look at optimizing the integration of the thin films onto gold and the incorporation of MIP films into micro-fabricated sensor arrays. —Phillip B. Espinasse