Surface acoustic wave (SAW) devices are widely used in sensing and biosensing but generally suffer from strong attenuation in liquid environments. Conventional approaches rely on reflectors to reduce these losses, yet these components remain difficult to optimize: limited device miniaturization, and increase fabrication complexity. Here, we introduce an innovative design strategy that integrates a phononic metasurface with tailored electromechanical properties of the substrate to generate a type of shear-horizontal (SH) surface resonance modes that exhibit strong lateral confinement and extremely low radiation into both the substrate bulk and the free surface, eliminating the need for reflectors. This approach enables highly tailorable surface acoustic resonances with distinctive enhanced dynamic strain-energy confinement leading to significantly higher quality factors than conventional SAW devices, particularly in water-loaded conditions. We show the fabrication and experimental validation of the proposed phononic metasurface-based SAW resonator and showcase its biosensing capabilities through real-time monitoring of cellular death.

Cet article présente une approche innovante dans le domaine de l'enseignement expérimental de l'électronique, adaptée aux contraintes du distanciel. Dans un contexte où les formations en ligne nécessitent des méthodes pédagogiques adaptées pour maintenir l'efficacité des apprentissages, cette approche propose une méthodologie structurée permettant aux étudiants de réaliser des travaux pratiques à distance. En s'appuyant sur la plateforme Keysight qui propose des outils de simulation et de mesure avancés accessibles en ligne, cette méthode vise à reproduire les conditions d'un laboratoire traditionnel tout en favorisant l'autonomie et l'interactivité. L’objectif principal est de permettre aux étudiants de manipuler des circuits électroniques de manière concrète en autonomie afin que l’apprenant soit moteur dans son apprentissage. Les premiers retours des étudiants mettent en évidence une amélioration significative de leur compréhension des concepts électroniques associés aux manipulations et une plus grande aisance dans la confrontation avec la partie manipulation et technique. Cette approche s'inscrit dans une volonté d'innovation pédagogique, visant à renforcer la réussite des étudiants dans un contexte d'enseignement hybride ou entièrement distanciel.

Highly specific detection of tumor-associated biomarkers remains a challenge in the diagnosis of prostate cancer. In this research, Maackia amurensis (MAA) was used as a recognition element in the functionalization of an electrochemical impedance-spectroscopy biosensor without a label to identify cancer-associated aberrant glycosylation prostate-specific antigen (PSA). The lectin was immobilized on gold-interdigitated microelectrodes. Furthermore, the biosensor’s impedance response was used to assess the establishment of a complex binding between MAA and PSA-containing glycans. With a small sample volume, the functionalized interdigitated impedimetric-based (IIB) biosensor exhibited high sensitivity, rapid response, and repeatability. PSA glycoprotein detection was performed by measuring electron transfer resistance values within a concentration range 0.01–100 ng/mL, with a detection limit of 3.574 pg/mL. In this study, the ability of MAA to preferentially recognize α2,3-linked sialic acid in serum PSA was proven, suggesting a potential platform for the development of lectin-based, miniaturized, and cost effective IIB biosensors for future disease detection.

Cet article présente le contenu et les objectifs d’une approche originale dans le domaine de l’innovation pédagogique numérique dans un enjeu de mutualisation, d’échanges et d’actions en faveur de la réussite des étudiants. Cette approche a été développée dans le cadre du projet OpenING (Ouverture du cycle Préparatoire aux Enseignements Numériques en écoles d’INGénieurs) porté par la Fondation partenariale Polytech au nom des écoles du réseau Polytech et retenue par le Ministère de l’Enseignement supérieur, de la Recherche et de l’Innovation dans le cadre d’un appel à projets lancé par l’ANR. Ce projet se veut être un véritable accélérateur pour l’enseignement hybride au sein des écoles du réseau Polytech. La motivation de la démarche proposée est de produire des grains pédagogiques dans différentes disciplines et notamment en électronique pour la remise à niveau (à minima) des primo-arrivants en étude supérieure. À l’aide de ces grains, l’apprenant pourra revoir des bases de la matière et s’autoévaluer, l’objectif final étant de permettre aux étudiants de se familiariser aux pratiques de formation en ligne "autonomes" par l’acquisition de notions, la proposition de quiz et d’exercices ciblés. L’originalité de ce projet est de permettre aux apprenants en plus de suivre des grains théoriques, de réaliser des travaux pratiques en ligne en utilisant les principaux appareils d’instrumentation et de mesure. Un retour des premiers apprenants est proposé en fin d’article.

Love wave (L-SAW) sensors have been used to probe cell monolayers, but their application to detect changes beyond the focal adhesion points on cell monolayers, as viscosity changes on the cytoskeleton, has not been explored. In this work we present for the first time a Love wave sensor with tuned penetration depth and sensitivity to potentially detect mechanical changes beyond focal adhesion points of cell monolayers. We designed and fabricated a Love wave sensor operating at 30 MHz with sensitivity to detect viscous changes between 0.89 and 3.3 cP. The Love wave sensor was modeled using an acoustic transmission line model, whereas the response of interdigital transducers (IDTs) was modeled with the Campbell’s cross-field circuit model. Our design uses a substrate with a high electromechanical coupling coefficient (LiNbO3 36Y-X), and an 8-µm polymeric guiding layer (SU-8). The design aims to overcome the high insertion losses of viscous liquid environments, and the loss of sensitivity due to the low frequency. The fabricated sensor was tested in a fluidic chamber glued directly to the SU-8 guiding layer. Our experiments with liquids of viscosity similar to those expected in cell monolayers showed a measurable sensor response. In addition, experimentation with SaOs-2 cells within a culture medium showed measurable responses. These results can be of interest for the development of novel cell-based biosensors, and novel characterization tools for cell monolayers.

The present work deals with the development of a Love-wave biosensor for the diagnosis of the modification of cell viscosity. The relevant device performance such as insertion loss, attenuation, phase velocity, and sensitivity needs to be analysed as a function of the device structure and also regarding the effect of the liquid loading. In this study, we used an analytical model based on the equation of motions for a Love wave propagating in a three-layer structure. We show that the effect of the viscous coupling leads to insertion losses and a phase shift that impact the acoustic ratio. A comparison between experimental and theoretical results showed a good agreement between the behaviours as it was observed for the phase shift vs. the insertion loss with a limited difference in values (3.11/3.09—experimental/simulation for the sensitivity to the viscosity for different insertion losses) due to the assumptions made on the model used.

Medical imaging has relied on ultrasound (US) as an exploratory method for decades. Nonetheless, in cell biology, the numerous US applications are mainly in the research and development phase. In this review, we report the main effects on human or mammal cells of US induced by bulk or surface acoustic waves (SAW). At low frequencies, bulk US can lead to cell death. Under specific intensities and exposure times, however, cell proliferation and migration can be enhanced through cytoskeleton fluidization (a reorganization of the actin filaments and microtubules). Cavitation phenomena, frequencies of resonance close to those of the biological compounds, and mechanical transfers of energy from the acoustic pressure could explain those biological outcomes. At higher frequencies, no cavitation is observed. However, USs of high frequency stimulate ionic channels and increase cell permeability and transfection potency. Surface acoustic waves are increasingly exploited in microfluidics, especially for precise cell manipulations and cell sorting. With applications in diagnosis, infection, cancer treatment, or wound healing, US has remarkable potential. More mechanotransduction studies would be beneficial to understand the distinct roles of temperature rise, acoustic streaming and mechanical and electrical stimuli in the field.

Surface-acoustic-wave (SAW) sensors have undergone outstanding developments during the last decades. However, for biosensing applications, they struggle to compete with optical sensing technologies. In this work, we present a Love-wave-based sensing platform that leverages the use of the local resonances of micropillars fabricated on the surface of the guiding layer. We demonstrate numerically and experimentally that the Love-wave interaction with the micropillars produces sharp attenuation dips in the transmission spectrum. These dips are associated with the excitations of flexural and torsional resonance modes of the pillars. We utilize these modes to achieve higher detection sensitivity of temperature variation and mass loading using sugar and microbeads concentrations in aqueous solutions. Integrating a lattice of micropillars into SAW-based devices offers a strong potential for detecting low particles concentrations.

There is considerable attention on the determination of prostate-specific antigen (PSA) glycosylation patterns for the early detection of prostate cancer, as it is one of the most reliable tumor biomarkers. In this study, the highly effective lectin-based biosensor utilizing gold interdigitated microelectrode was developed as a sensing transducer, coupled with electrochemical impedance spectroscopy (EIS) for the sensitive detection of biomolecules event on the device. The self-assembled monolayer using 11-mercaptoundecanoic acid was utilized to modify the sensor surface for the conjugation of Maackia amurensis lectin as biorecognition elements. The analytical analysis of the developed lectin biosensor with PSA glycosylation through impedimetric measurement exhibited a linear detection ranging from 100 pg/mL to 100 ng/mL and attained a detection limit of 27.6 pg/mL.

Prostate cancer is currently diagnosed using the conventional gold standard methods using prostate-specific antigen (PSA) as the selective biomarker. However, lack of precision in PSA screening has resulted in needless biopsies and delays the treatment of potentially fatal prostate cancer. Thus, identification of glycans as novel biomarkers for the early detection of prostate cancer has attracted considerable attention due to their reliable diagnostic platform compared with the current PSA systems. Therefore, biosensing technologies that provide point-of-care diagnostics have demonstrated the ability to detect various analytes, including glycosylated micro- and macro-molecules, thereby enabling versatile detection methodologies. This highlight article discusses recent advances in the biosensor-based detection of prostate cancer glycan biomarkers and the innovative strategies for the conjugation of nanomaterials adapted to biosensing platforms. Finally, the article is concluded with prospects and challenges of prostate cancer biosensors and recommendations to overcome the issues associated with prostate cancer diagnosis.

We present a finite element (FE) based model to accurately investigate the dispersion and attenuation of Love waves in a multilayered structure made of a piezoelectric substrate, a guiding layer, and a viscous fluid. The numerical model solves the general form of the wave equations that includes the materials anisotropy, piezoelectricity, and viscoelasticity. We express the wave equations for elastic waves in a particular formulation in order to solve an eigenvalue problem where the eigenvalue is the complex wavenumber k from which we can derive the phase velocity [ω/Re(k)] and the attenuation rate [Im(k)]. The numerical model enables us to study the effects of the interdigitated electrodes, the materials viscoelasticity and piezoelectricity, and the fluid's viscosity on the wave phase velocity and attenuation. Our FE based model will facilitate optimizing the design of anisotropic piezoelectric platforms for Love waves propagation under viscous fluid loading.

In this work, we investigate the evolution of the properties of a pillar phononic crystal in order to simplify the fabrication process by reducing the thickness of the layer. The structure is constructed by stacking alternate layers of SiO2 and Tungsten. The reduction of the dimensions moves the band gap to the upper frequencies and it is possible to adjust its aperture with the ratio comparing the radius of the cylinder with the layers' thickness. On a substrate, the pillars give resonant modes that can be excited by shear surface waves and gives a sharp peak in the transmission spectrum of the surface wave with a very high quality factor. We also study the theoretical mass sensitivity of the device and we propose a numerical method to determine the theoretical maximum sensitivity that could be obtain by the pillars system. This pillar based metasurface presents a very promising mass sensitivity and a possible way to increase the performance of SAW bio-sensors.

We present a design of a pillared phononic crystal based structure for Love wave manipulation to achieve high mass sensitivity. The structure is made of phononic micro-pillars constructed by stacking tungsten and SiO2 layers, distributed on a substrate designed for Love wave propagation. The multilayered pillar allows the creation of bandgaps, which leads to the existence of resonant modes where the elastic energy is confined within the SiO2 free surface layer of the pillar. We study particularly a resonant mode where this layer exhibits torsional mechanical motion which can only be excited by shear horizontal surface waves. We show that Love wave interaction with the torsional mode gives rise to a sharp attenuation in the surface wave transmission spectrum with a high quality factor. We also study the variation of the mass sensitivity of the system by evaluating the resonant mode's frequency shift induced by a mass perturbation using two theoretical approaches: a perturbation theory based approximation and a numerical method. The system presents very promising mass sensitivity which provides an interesting approach to increase the detection performance of Love wave based bio-sensors.

In this work, we investigate the sensitivity of a pillar based metasurface in order to understand the behavior of the system in real tests conditions where the mass perturbation will not be homogeneous on all the system. The structure we study is composed in stacking alternate layers of Silica and Tungsten and presents a torsional resonant mode which presents a high quality factor and a high mass sensitivity, in a case of a homogeneous perturbation. In a case of a non-homogeneous mass-perturbation over the pillars, each pillar gives a contribution to the signal perturbation under the form of a shifted peak. These results show that each pillar gives a contribution to the output signal and that the high quality factor of the structure allows to distinguishing the different perturbations.

In this work we present the development of an integrated microfluidic platform addressing several challenges. The sensor array combines a dual Rayleigh wave and Love wave for the diagnosis of the modification of cell viscoelasticity. Based on simulations taking into equations of motion and Navier-Stokes equation for the viscous liquid region, we evaluate and correlate the Love surface acoustic wave sensing part in order to enhance the sensitivity. The results corroborate the idea that the whole measurement system must be considered to develop an integrated optimized analysis system.

We present a design of phononic crystal based on pillars distributed on a substrate surface in which each pillar is constructed by a periodic stacking of PMMA and silicon layers. The pillar behaves like a one-dimensional phononic crystal which allows the creation of band gaps that prohibit wave propagation along the pillar. Thanks to this property, we show that confined modes are produced at the pillar-substrate interface which couples with surface acoustic waves (SAW) and causes their attenuation. Furthermore, by tailoring a defect inside the phononic pillar, we reveal the possibility to create confined cavity modes inside the band gap which can strongly couple with SAW. The cavity modes can be excited by SAW and the coupling produces sharp SAW transmissions. Additionally, we demonstrate that the coupling between the cavity modes and the confined modes at the pillar-substrate interface can give rise to a Fano-like resonance. We also evidence the possibility of generating an acoustic analogue of electromagnetically induced transparency for SAW with high transmission in a narrow bandwidth. The system presents perspectives for the design of high-quality-factor phononic excitation for optomechanic devices and phonon circuits based on SAW manipulation.

Hydrogen sensors are of increasing importance as hydrogen gas is a promising alternative as an energy carrier.Unfortunately, hazardous leaks have to be detected quickly and safely since hydrogen is highly explosive for concentrations in the air within 4 and 75%.This article reports the experimental results of a new scheme of hydrogen detection based on a nanostructured catalyst PdPt/Al2O3, a Surface Acoustic Wave (SAW) transducer in a differential configuration, and a signal conditioning circuit.The results show that the scheme of detection presents a linear response, a sensitivity of 5,41V/%(H2) and a low drift, in the range of 0.2 -2%, with a response time estimated to 10 seconds.

Chagas disease (CD), which mostly affects those living in deprived areas, has become one of Latin America's main public health problems. Effective prevention of the disease requires early diagnosis, initiation of therapy, and regular blood monitoring of the infected individual. However, the majority of the Trypanosoma cruzi infections go undiagnosed because of mild symptoms, limited access to medical attention and to a high variability in the sensitivity and specificity of diagnostic tests. Consequently, more affordable and accessible detection technologies capable of providing early diagnosis and T. cruzi load measurements in settings where CD is most prevalent are needed to enable enhanced intervention strategies. This work analyzes the potential contribution of biosensing technologies, reviewing examples that have been tested and contrasted with traditional methods, both serological and parasitological (i.e., molecular detection by PCR), and discusses some emerging biosensing technologies that have been applied for this public health issue. Even if biosensing technologies still require further research efforts to develop portable systems, we arrive at the conclusion that biosensors could improve the accuracy of CD diagnosis and the follow-up of patients' treatments in terms of the rapidity of results, small sample volume, high integration, ease of use, real-time and low cost detection when compared with current conventional technologies.

We present a phononic crystal to achieve efficient manipulation of surface acoustic waves (SAW). The structure is made of finite phononic micro-ridges arranged periodically in a substrate surface. Each ridge is constructed by staking silicon and tungsten layers so that it behaves as one-dimensional phononic crystal which exhibits band gaps for elastic waves. The band gap allows the existence of resonance modes where the elastic energy is either confined within units in the free end of the ridge or the ones in contact with the substrate. We show that SAW interaction with localized modes in the free surface of the ridge gives rise to sharp attenuation in the SAW transmission, while the modes confined within the ridge/substrate interface cause broad band attenuations of SAW. Furthermore, we demonstrate that the coupling between the two kinds of modes within the band gap gives high SAW transmission amplitude in the form of Fano-like peaks with high quality factor. The structure could provide an interesting solution for accurate SAW control for sensing applications, for instance.