Quartz On-chip for Virus Detection

Project Information

QOVID

Grant agreement ID: 101082079

DOI

10.3030/101082079

Project closed

EC signature date 5 September 2022

Start date 1 October 2022

End date 31 March 2024

Funded under

• European Research Council (ERC)

Total cost

No data

EU contribution

€ 150 000,00

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 1 - QOVID (Quartz On-chip for Virus Detection)

Reporting period: 2022-10-01 to 2024-03-31

Summary of the context and overall objectives of the project

The coronavirus disease 2019 (COVID-19) has turned into a global pandemic that has caused more than 4 million deaths worldwide as well as massive perturbations at all levels of life, from public administrations and markets to our daily social interactions. Like other emerging virus outbreaks, such as Chikungunya, Zika, or Middle East respiratory syndrome coronavirus (MERS-CoV) viruses, COVID-19 requires a complex strategy to stop its propagation and eventually defeat it. International health authorities recommend prevention and containment measures. This includes social distancing, isolation of contagious cases, and the stringent implementation of hygiene. However, they require strict execution to be effective. In addition, longer-term solutions like vaccine development require significant investment and research to understand the molecular mechanism by which the virus attacks the body and its cells.
The primary means of diagnosis for COVID-19 and other respiratory viruses are:

-Oropharyngeal and nasopharyngeal swab procedures that use biological methods like antibody tests.
-Real-time reverse transcription-polymerase chain reaction (RT-PCR).
-Antigen tests.

However, the successful engineering of these tests involves understanding the components of the virus that require sample pretreatment or labeling, like extraction of the viral DNA or RNA to match a complementary strand. In this context, developing a precise, rapid, intelligent, and cost-efficient test to determine whether a person has been infected with COVID-19 or other viruses is essential to prevent future rebounds of infections and help control the pandemic. Among label-free biosensors, piezoelectric mechanical sensors have unique advantages, i.e. i) the direct measurement of the crystal deformation by electrical methods and ii) the absence of interferences with biomolecules, compared to optical systems. In this regard, α-quartz is the best piezoelectric sensing material with a vast quality factor (Q > 106), exceptional temperature stability, and deficient phase noise. However, to date, α-quartz applied to microelectronics is exclusively synthesized by hydrothermal methods, which produce giant crystals, making it impossible to decrease their size below a thickness of 10 µm. For most applications, these crystals need to be bonded on Si substrates.
The QOVID project aims to make a proof of concept based on the ERC SENSiSOFT α-quartz devices to develop a biosensor that biologists and biomedical faculty can use to detect viruses-mediated biological processes. In short, QOVID wants to scale up the production of α-quartz resonating nano-structured devices with thicknesses between 200 nm and 1 µm, 10 to 50 times thinner than those obtained by top-down technologies on bulk crystals. As a result, we expect to fabricate a new generation of on-chip quartz piezo MEMS capable of measuring tiny masses through a variation in the resonant frequency, piezo-generated charges, or impedance without damping phenomena. Notably, the QOVID project's ambition is to generate new tools and methodologies that can be applied to other relevant emerging pathogens and prepare us to confront future pandemics.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Throughout the QOVID project, we meticulously studied and achieved significant milestones in criteria such as robustness, reproducibility, low cost, and mechanical quality factors. These achievements, a direct result of our understanding of viscous damping, have paved the way for precise molecular signature detection in liquid conditions using quartz-based resonators. The main goals we have accomplished are:

1. A significant breakthrough in our project was the successful integration of high-quality epitaxial piezoelectric α-quartz thin films on silicon, leading to the engineering of the first epitaxial quartz-based micro and nanoelectromechanical (MEMS) device sensor. With its unprecedented low mass detection sensitivity on the pg range in a liquid medium, this sensor signifies ultra-sensitive quartz devices that can measure tiny masses (<10 pg) or forces through a variation in the resonant frequency.
2. We have designed an integrated microfluidic resonant cavity system adapted to the quartz piezoelectric electromechanical system to improve the response in liquid conditions and fulfill criteria such as reproducibility, low cost, and robustness. This technological improvement allows us to perform real-time measurements in a biological environment.
3. We have set up a robust and versatile bio-conjugation system to determine the ability of quartz resonators to measure selective molecular interactions. The system consists of a sandwich multilayer made up of the covalent immobilization of a SypCatcher/SpyTag complex linked to an avidin molecule, namely SpyAvidn, allowing a single biotin interaction in its tetrameric structure. We used the detection of the Chikungunya virus to control the selective recognition of biomolecules with our recognition layer. The research team has decided to work with the Chikungunya virus as it represents an emerging virus due to global warming and poses a pandemic risk in the near future.

As a result, the team is now measuring the selective binding of Chikungunya virus-related particles and obtaining the kinetics of virus-receptor binding. These experiments will enable us to determine the sensitivity of molecular interactions that can be detected using our α-quartz resonating nano-structured devices.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Among all current solutions provided by the industrial and academic players, our epitaxial piezoelectric α-quartz/Si MEMS stands out as a novel and unique technology. Manufactured with CMOS-compatible processes, it offers proper single-chip solutions for ultra-sensitive mass (pg range) sensor devices while retaining small size and low cost. The developed quartz nanoscale On-chip sensor is green (low toxicity, biocompatible, and energy consumption) for the mass market and biomedical applications. At this stage of development, our concept can offer unique advantages compared to all other solutions:

1. A bottom-up fabrication methodology that permits much thinner epitaxial quartz films on SOI substrate (up to 4-inch wafer), with thicknesses between 200 and 1000 nm.
2. A coherent quartz/silicon interface and a controlled nano-structuration present higher sensitivities while preserving the device's mechanical quality factor.
3. Using scalable lithographic processes and a simple design that ensures crystal quality preservation, piezoelectric functionality, and the quality factor of the active quartz layer reduces the entire resonator's complexity and cost.

With these promising results, the QOVID project is poised to transform these innovation findings into a marketable commercial product for the medical and biotechnological sectors.Our goal now is to continue the development of a low-cost and sensitive virus detection tool, a sensor terminal composed of ultra-thin high-quality factor piezoelectric epitaxial quartz MEMS with a nanometric motion from MHz to GHz integrated on silicon technology and on a modular PCB technology ready to use for biological applications.

Main objectives of QOVID project