Resistive, unipolar and ordered ZnO nanowire arrays for flexible sensors adapted to biological media – ROLLER

The project ROLLER aims at developing a composite material consisting of ordered, resistive, and unipolar ZnO nanowires (NWs) embedded in a polymer matrix for the realization of pressure or flow flexible sensors adapted to biological media. This type of composite material in the form of in-vivo or ex-vivo micro-sensors are specifically developed for applications related to medical diagnostics and instrumentation as well as for their integration in e-health connected objects (healthcare and sport performance monitoring…).
The main objectives of the project are dedicated to the modeling, design, fabrication, advanced multiscale characterizations and integration of these composite structures.
The initial phase devoted to the modeling by finite element method will allow us to correlate the electrical and mechanical impedances as well as the electromechanical coupling to the intrinsic characteristics of the components (NWs and polymer matrix) and of their geometrical parameters. The control of these quantities is capital because they directly affect the final performances of the sensors (sensitivity, impedance matching with the medium, frequency behaviour, measurement range, electric output type…). These modeling tools will further allow us to define the reference composite structures for the subsequent phases devoted to the characterization of the main deformation modes under static and dynamic regimes.
In order to fabricate the composite structures, innovative technological processes in a cleanroom environment combined with original approaches using low-cost, low-temperature, and surface scalable chemical deposition techniques will be developed. The systematic determination and monitoring of the doping and polarity properties as well as of the elastic, piezoelectric (PZ), and dielectric properties at the local and macroscopic scales in these arrays will be a crucial challenge for their correlation with the theoretical modeling and for their exploiting in that new generation of flexible sensors. Specific microscopic and macroscopic characterization methods will thus be developed to estimate the elastic, PZ and dielectric parameters and to correlate them with the microscopic properties of the NWs. The macroscopic method, similarly to the one used for the characterisation of PZ materials, will be based on the frequency analysis of the electrical impedance of references samples for the main deformation modes, from which reference values by direct measurement of the elastic (mechanical bench under compression and shear), PZ (electromechanical coupling test bench) and dielectric properties will be inferred. The microscopic properties of the NWs in terms of doping and polarity will be determined in the form of profile and maps by advanced characterization techniques (TEM/STEM: EDS, CBED, resonant XRD using synchrotron radiation, AFM: SSRM, SCM, PFM, KPFM, electrical transport…).
At last, a demonstrator integrating a pressure or flow flexible micro-sensor will be designed, fabricated and characterized. It will be composed of the composite material deposited on a flexible substrate and will be solicited under its bending deformation mode.
The present project will benefit from the unique and multidisciplinary skills of the consortium in nanomaterials science and engineering as well as in the design and characterization of multiphysics coupled systems. It will take profit from the strong development of nanomaterials correlated with an actual system approach, integrating at the onset of the modelisation phase the functionalities expected for the biological application targeted. The beneficial effects, both fundamental and applicative, should lead to the huge development of basic knowledges as well as to a technological breakthrough in the field