Monolithically integrated dye-doped PDMS long-pass filters for disposable on-chip fluorescence detection.
We report the fabrication of high quality monolithically integrated optical long-pass filters, for use in disposable diagnostic microchips. The filters were prepared by incorporating dye molecules directly into the microfluidic chip substrate, thereby providing a fully integrated solution that removes the usual need for discrete optical filters. In brief, lysochrome dyes were added to a poly(dimethylsiloxane) (PDMS) monomer prior to moulding of the microchip from a structured SU-8 master. Optimum results were obtained using 1 mm layers of PDMS doped with 1200 microg mL(-1) Sudan II, which resulted in less than 0.01% transmittance below 500 nm (OD 4), >80% above 570 nm, and negligible autofluorescence. These spectral characteristics compare favourably with commercially available Schott-glass long-pass filters, indicating that high quality optical filters can be straightforwardly integrated into the form of PDMS microfluidic chips. The filters were found to be robust in use, showing only slight degradation after extended illumination and negligible dye leaching after prolonged exposure to aqueous solutions. The provision of low cost high quality integrated filters represents a key step towards the development of high-sensitivity disposable microfluidic devices for point-of-care diagnostics.
Hofmann
Oliver
O
Molecular Vision Ltd., 90 Fetter Lane, London EC4A 1JP, UK.
Wang
Xuhua
X
Cornwell
Alastair
A
Beecher
Stephen
S
Raja
Amal
A
Bradley
Donal D C
DD
Demello
Andrew J
AJ
Demello
John C
JC
D001391:Azo Compounds; D004129:Dimethylpolysiloxanes; D005453:Fluorescence; D046210:Microfluidic Analytical Techniques; D044085:Microfluidics; D009757:Nylons
D001391:Azo Compounds; D004129:Dimethylpolysiloxanes; D009757:Nylons; C085707:poly(dimethylsiloxane)-polyamide copolymer; C033003:sudan red