The PHOTO-SENS system consists of a desktop reader, which can be used in combination with disposable microfluidic cartridges containing hybrid PICs. To reduce the manufacturing costs of the cartridge, the price of the PIC has to be reduced and the manufacturing and assembly process has to be improved. Design optimization of the waveguide circuitry and an improved cartridge integration concept enabled a reduction of the PIC footprint by a factor of 8 without sacrificing functionality or sensitivity, resulting in an equivalent reduction of the cost per chip. Wafer scale processes for hybrid integration of components by thermocompression bonding, soldering, and adhesive bonding have been developed based on laser-assisted local heating of substrate wafers. Furthermore, novel processes for wafer scale material-selective chemical surface modification and singulation by stealth dicing have been developed. Together, all of these processes constitute a complete and scalable process flow for wafer scale production of hybrid biosensor PICs.
The next step is the assembly of the PIC in the microfluidic cartridge. First, a basic cartridge has been designed and fabricated, with which the concept of chip-cartridge integration has been validated. Leak tightness, and optical and electrical functionality of the basic cartridge has been confirmed. Next, a microfluidic cartridge for DNA assays has been developed, comprising a sample injection port, and blister pouches with assay buffers and reagents. The cartridge also features a heating element, degassing functionality, cavities for flow front detection, and a waste reservoir. Moreover, the cartridge provides electrical, mechanical, and fluidic interfaces with the tabletop readout instrument.
The instrument contains mechanics, electronics, and software for cartridge handling, heating, optical actuation and readout of the PIC, and controlling liquid flows. Three prototype instruments have been built, and were tested in combination with the microfluidic cartridge. Measurements using solutions with different salt concentrations have confirmed the functionality of the instrument, the microfluidic cartridge, and the hybrid PICs.
Three bacterial aquaculture pathogens were selected for assay development. DNA biomarkers were identified, corresponding primer-probe sets were designed, and qPCR assays were developed that could detect biomarker concentrations down to 5 copies/µL. One pathogen biomarker was also detected using the hybrid PIC platform. This is the first successful demonstration of biosensing on the hybrid PIC platform.
Dissemination of project results has taken place through different channels. The main dissemination publications are:
- 3 theses
- 3 white papers
- 6 conference presentations
- 1 project poster
- 1 peer reviewed scientific paper
Despite the impressive technical progress, the system as a whole is not yet sufficiently advanced to be commercialized shortly after finalization of the project. This also has an impact on the exploitation plans of the project partners. In particular, the first generation of PIC biosensor products will be based on passive PICs. Furthermore, Surfix has decided to focus on medical (cancer) diagnostics as their primary target market. TunaTech will serve the aquaculture market with their qPCR based solutions, while looking for opportunities to continue the development towards chip-based testing. For PHIX, CSEM, and LRE, their participation in PHOTO-SENS has resulted in the development of new exploitable processes and knowledge, which enables them to expand their portfolio of services. Thus, the consortium will not jointly market hybrid PIC based pathogen detection tests. Instead, the partners will focus on their individual plans to exploit and commercialize the project results.
