The PYTHIA project aims at the development of a novel optoelectronic transducer based on broad-band Mach-Zehnder Interferometry (BB-MZI), suitable for wafer scale fabrication, functionalisation and encapsulation and its application to the early diagnosis of human diseases through the label-free, multi-analyte detection of gene mutations and proteins.
The PYTHIA biochip is the only device in the world where all active and passive optical components (light source, waveguides, photodetector) are monolithically integrated all in the same Si chip, and fabricated by standard silicon technologies only.
The electro-optical bio-transducer, addresses all key issues of existing optical biochips: miniaturisation, ultimate integration level, improved sensitivity and detection limits, repeatability, and adaptability to various diagnostic schemes (genomics and proteomics).
The PYTHIA biochip becomes the only truly integrated, fully-compact, all-Si optical biosensor that can be readily implemented to mass-production.
The biochip, controlled by accompanying user-friendly software, will be capable of simultaneous multi-analyte and real-time detection, with an assay duration that will not exceed a few minutes with minimal blood sample volumes or specimens.
The PYTHIA optoelectronic transducer consists of a VISNIR light source and a waveguide monolithically fabricated on a Si wafer and patterned in two arms. Its principle of operation is the spectroscopic interference due to the optical path difference between the reference and properly functionalised sensing arm originating from biochemical events. The signal recording is realised either via an also monolithically fabricated photodetector or via an external spectrophotometer.
The basic biosensor scheme allows for the development of arrays consisting of individually functionalised light source/optical waveguide series coupled to a single detector for multiplexing operation.
Wafer-scale encapsulation along with an appropriately designed microfluidic system allow for the easy delivery of the samples and ensure the facile contact with the external low-noise electronic components. The encapsulated array is fixed on a cartridge ready to be manually inserted to its final position in the housing.
The electrical and optical characterisation of the first batch of optoelectronic transducers provided a solid confirmation of the BB-MZI concept and useful information for the design optimisation of the biosensor chips. The transducers were functionalised and encapsulated with a microfluidic cell to be possible to evaluate them in real conditions. For the Biotin- Streptavidin model assay, the detection of streptavidin in the picomolar range was easily demonstrated, which is comparable with the state of the art values for labelfree biosensors.
The progress in the design and fabrication of the biochip along with the preliminary results obtained so far are convincing that the PYTHIA biochip and measuring apparatus will be able to diagnose diseases at an early stage, determine whether one will suffer from hereditary diseases and provide head-up warnings for one's well-being.