0000000000013502
AUTHOR
Thérèse Leblois
Formation Kinetics of Mixed Self-Assembled Monolayers of Alkanethiols on GaAs(100)
International audience; We report on the formation kinetics of mixed self-assembled monolayers (SAMs) comprising 16-mercaptohexadecanoic acid (MHDA) and 11-mercapto-1-undecanol (MUDO) thiols on GaAs(100) substrates. These compounds were selected for their potential in constructing highly selective and efficient architectures for biosensing applications. The molecular composition and quality of one-compound and mixed SAMs were determined by the Fourier transform infrared absorption spectroscopy measurements. The formation of enhanced-quality mixed SAMs was investigated as a function of the molecular composition of the thiol mixture and the proportion of ethanol/water solvent used during thei…
Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometry Methods
International audience; Widely used in microelectronics and optoelectronics; Gallium Arsenide (GaAs) is a III-V crystal with several interesting properties for microsystem and biosensor applications. Among these; its piezoelectric properties and the ability to directly biofunctionalize the bare surface, offer an opportunity to combine a highly sensitive transducer with a specific bio-interface; which are the two essential parts of a biosensor. To optimize the biorecognition part; it is necessary to control protein coverage and the binding affinity of the protein layer on the GaAs surface. In this paper; we investigate the potential of a specific chemical interface composed of thiolate molec…
Thermal and conductivity dependence of GaAs based acoustic biosensors
GaAs BAW sensors using shear acoustic waves were developed for biological detection and quantification. The sensor consists of a 50–350µm thick membrane where thickness shear acoustic waves were produced with a lateral field excitation (LFE). The LFE electrode arrangement is located on one side of the membrane. The other side is dedicated for proteins or cells capture through a bio-functionalized interface formed on the GaAs surface. Sensitivity of this type of sensor had been evaluated by modeling to 0.1ng.Hz−1. Detection needs to be done in liquid environment with complex biological analytes such as blood or plasma. These analytes can inevitably induce temperature and surface charge varia…
Reconstitution of a protein monolayer on thiolates functionalized gaas surface
International audience; In the aim to realize an efficient resonant biosensor, gallium arsenide (GaAs) presents many advantages. In addition to its properties of transduction, GaAs is a crystal for which microfabrication processes were developed, conferring the possibility to miniaturize the device and integrate electronic circuit. Moreover, the biofunctionalization could be realized on the crystalline surface without layer deposition, constituting a real advantage to perform reusable sensor. The functionalization of GaAs surface was engaged in order to immobilize a protein monolayer on this substrate. Functionalization was done using a mixed self assembled monolayer of thiolate molecules. …
Regenerable ZnO/GaAs Bulk Acoustic Wave Biosensor for Detection of Escherichia coli in “Complex” Biological Medium
A regenerable bulk acoustic wave (BAW) biosensor is developed for the rapid, label-free and selective detection of Escherichia coli in liquid media. The geometry of the biosensor consists of a GaAs membrane coated with a thin film of piezoelectric ZnO on its top surface. A pair of electrodes deposited on the ZnO film allows the generation of BAWs by lateral field excitation. The back surface of the membrane is functionalized with alkanethiol self-assembled monolayers and antibodies against E. coli. The antibody immobilization was investigated as a function of the concentration of antibody suspensions, their pH and incubation time, designed to optimize the immunocapture of bacteria. The perf…
Specificity and Sensitivity Characterization of a Gallium Arsenide Resonant Bio-Sensor
International audience; The characterization of the performances of a Gallium Arsenide (GaAs) based biosensor, in terms of sensitivity and specificity, is reported. The design of the sensor consists in a resonant membrane fabricated in GaAs crystal that operates at shear modes of bulk acoustic waves generated by lateral field excitation. The transducer element was fabricated by using typical clean room microfabrication techniques. The backside of the membrane is functionalized by a self-assembled monolayer (SAM) of alkanethiols to immobilize bio-receptors, which will allow the specific capture of the analyte of interest. The theoretical sensitivity of the sensor had been determined by model…
Critical Influence of Dielectric Sensitive Material and Manufactured Process in Microwave Gas-Sensing: Application of Ammonia Detection with an Interdigital Sensor
In this paper, authors propose a study on microwave gas sensors and the influence of critical key parameters such as the sensitive material and the circuit conception process. This work aims to determine the influence of these parameters on the quality of the final response of the microwave gas sensor. The fixed geometry of the sensor is a microstrip interdigital capacitor coated with a sensitive layer excited with two 50 Ω SMA ports. The sensitive material has been chosen in order to interact with the target gas: ammonia. Indeed, this gas interacts with phthalocyanine and metal oxides like hematite, TiO2. To explore the effect of the circuit manufacturing process, three series of samples a…
Deposition and characterization of ZnO thin films on GaAs and Pt/GaAs substrates
Abstract This work reports the deposition and characterization of piezoelectric ZnO thin films on semi-insulating GaAs substrates for the fabrication of bulk acoustic waves sensors. ZnO films are deposited at 350 °C and low deposition rate using reactive radio frequency magnetron sputtering. The use of a Pt bottom electrode, between ZnO and GaAs, with and without Ti buffer layer, as well as the effect of the substrate crystallographic orientation are investigated. The characterization of the deposited films is performed to determine the optimal parameters for obtaining high-quality films and ZnO residual conductivity. ZnO films are textured along the c-axis for all GaAs cuts. The highest st…
An optimal dimensioning method of a green wall structure for noise pollution reduction
International audience; This paper concern the optimization of a multilayered green wall structure including substrate and foliage in order to reduce as much as possible backward noise reflection and forward transmission from the wall. Each component involved in the wall structure is fully characterized experimentally to get its transfer matrix. Simulation demonstrated that foliage layer superimposed to substrate layer doesn’t affect the transmission losses but contributes greatly to the increase of return losses of the green wall structure. To achieve the best performances in terms of return and forward losses as well as frequency bandwidth, the methods of optimization are discussed inclu…
Automated Cancer Marker Characterization in Human Plasma Using SUrface PLASMON Resonance in Array combined with Mass Spectrometry (SUPRA-MS)
International audience; The combination of Surface Plasmon Resonance technology with Mass Spectrometry becomes a key method for the characterization of targeted proteins in the fields of diagnosis and functional proteomics. We demonstrated in this work the ability of our SPRi-chip to capture targeted protein in biological fluids and in situ analyze by MS and MS/MS modes through automated procedure to go beyond classical immunoassays. Here, we established a proof of concept of SUPRA-MS for the detection, the identification and the characterization of a potential breast cancer marker.