Cavity Enhanced Absorption Spectroscopy (CEAS)
Absorption spectroscopy is widely used for chemical and biological assay. The Beer–Lambert law states that the absorbance is proportional to the path length of measurement and so the sensitivity of absorption measurements can be improved by increasing the path length. The sensitivity of absorption spectroscopy has been greatly improved by the use of optical cavities. These have used high reflectivity dielectric mirrors to form an optical cavity around the sample which allows light entering through the back of one of the mirrors to be essentially multipassed many times through the sample and thus greatly increase the effective path length of measurement. Cavity enhanced absorption spectroscopy (CEAS) measures the time integrated intensity of exiting the cavity and has advantages of low cost.
Anasyst is pioneering next-generation CEAS for liquid based sensing. We have previously demonstrated use of CEAS with a conventional 2 mm cuvette across a range of analytes at visible wavelengths and achieved ~50 fold improvement in sensitivity compared to conventional UV-visible spectroscopy using a low cost system. We have also shown use of the CEAS technique as a detector for HPLC measurements and demonstrated ~50-70 fold improved sensitivity over a conventional system.
Anasyst is pioneering next-generation CEAS for liquid based sensing. We have previously demonstrated use of CEAS with a conventional 2 mm cuvette across a range of analytes at visible wavelengths and achieved ~50 fold improvement in sensitivity compared to conventional UV-visible spectroscopy using a low cost system. We have also shown use of the CEAS technique as a detector for HPLC measurements and demonstrated ~50-70 fold improved sensitivity over a conventional system.
Microfluidics
Microfluidics involves the handling of small volumes of fluids within chip based devices and offers advantages of lower sample and reagent consumption, low cost and high level of automation for sophisticated fluid operations with minimum variability. A variety of substrates can be used for fabrication of microfluidic devices including glass and polymer. Polymer devices have particular advantages of low cost and biocompatibility.
Within the EU DVT-IMP project, a point-of-care (POC) system was prototyped to aid diagnosis of Deep Vein Thrombosis and Pulmonary Embolism. The developed system includes a disposable microfluidic cartridge, comprising impedimetric transducer immobilised with single-chain antibody for recognition of d-dimer marker, and a reader system. The impedimetric transducer element was fabricated using clean room processes. Metallisation was carried out using sputtering and patterning of metal electrodes was achieved using lithography followed by etching. The polymer microfluidic body was fabricated using hot embossing and, for higher volume, micro-injection moulding. Impedimetric detection offers advantages of label-free multi-analyte detection and is applicable to a variety of analytes from small molecules of 100s of Daltons to large 2-5mm particles such as bacteria.
Within the EU DVT-IMP project, a point-of-care (POC) system was prototyped to aid diagnosis of Deep Vein Thrombosis and Pulmonary Embolism. The developed system includes a disposable microfluidic cartridge, comprising impedimetric transducer immobilised with single-chain antibody for recognition of d-dimer marker, and a reader system. The impedimetric transducer element was fabricated using clean room processes. Metallisation was carried out using sputtering and patterning of metal electrodes was achieved using lithography followed by etching. The polymer microfluidic body was fabricated using hot embossing and, for higher volume, micro-injection moulding. Impedimetric detection offers advantages of label-free multi-analyte detection and is applicable to a variety of analytes from small molecules of 100s of Daltons to large 2-5mm particles such as bacteria.