The project is based on the synergies of key technologies:
- Microfluidic technologies to provide a miniaturised device capable of sample purification and pre-concentration;
- Biochemistry and surface functionalisation, using aptamers and antibodies;
- Photonic resonators integrated in smart system for highly sensitive detection;
- Smart systems for the integration in the production chain.
Major achievements of the project:
- Development of photonic sensors
The photonic device proposed in this project is based on a low cost Si-based fully integrated optical sensor. During the first year of the project we designed, developed and tested two types of photonic sensors in order to define their performance in term of an Aflatoxin M1 sensor. The first design is based on SiN asymmetric Mach-Zehnder interferometers (aMZI) developed by LioniX, while the second sensor is based on SiON microring resonators (mRR) and developed jointly by FBK and UniTN.
Anti-aflatoxin aptamers were immobilized by FBK on the detector surface for the capture and detection of aflatoxin previously purified on the antibody-functional surfaces. The aptameric layer captures around 1013 aflatoxin molecules per cm2, matching the requirements to achieve the lowest limit of detection in EU regulation. The reusability of the aptameric layer has also been tested, showing a significant reduction of the binding efficiency after 5 regeneration cycles (SiON surfaces) or 10 regeneration cycles (Si3N4 surfaces), and therefore opening the promising perspective of using the sensor more than once, reducing the overall analysis cost.
We obtained a Limit Of Detection (LOD) of 0.8 10-6 Refractive Index Units (RIU) and 1.6 10-6 RIU in the case of aMZI and mRR, respectively. Preliminary Aflatoxin sensing measurements are also available. Integration of VCSEL sources and photodiodes by means of heterogeneous assembly will provide a module which is simple to use and without the need for complex alignment procedures, where only electrical contacts are needed to connect the sensor to the system.
- Development of microfluidic components
Sample preparation, (i.e. sample clean-up, extraction and pre-concentration), has been the main limiting factor of automatic and on-line analysis systems integration in the dairy industry. Clean-up kits available on the market are labour intensive and require a skilled operator to perform the procedure and therefore an automated procedure greatly contributes to the overall value of the system. In the project, this will be achieved with a joint activity of ACREO, EPIGEM and FBK using a micro/milli fluidic system, able to manage milk sample quantities of millilitres that will be moved, concentrated and interconnected with the sensor with a range of commercially proven interconnection and packaging technologies available to the consortium. The main purpose of the sample preparation stage is to clean the milk sample from unwanted components like fats, which may interfere with the following stages and cause clogging of the system, and to concentrate and make the toxin available for detection. Then, sample preparation can be schematically divided in the following steps: fat removal, aflatoxin extraction, pre-concentration and elution.
Sensor packaging with integral flow cells, has been designed and fabricated. This packaging can be reversibly sealed to the main microfluidics processor board using Epigem’s microseal technology.