Jean-François Manceau

Detection and High-Precision Positioning of Liquid Droplets Using SAW Systems

The capability to accurately handle liquids in small volumes is a key point for the development of lab-on-chip devices. In this paper, we investigate an application of surface acoustic waves (SAW) for positioning micro-droplets. A SAW device based on a 2 times 2 matrix of inter-digital transducers (IDTs) has been fabricated on a (YXl)/128deg LiNbO3 substrate, which implies displacement and detection in two dimensions of droplets atop a flat surface. Each IDT operates at a given frequency, allowing for an easy addressing of the active channel. Furthermore, very low cross-talk effects were observed as no frequency mixing arose in our device. Continuous as well as pulsed excitations of the IDTs have been studied, yielding, respectively, continuous and step-by-step droplet displacement modes. In addition, we also have used these two excitation types to control the velocity and the position of the droplets. We also have developed a theoretical analysis of the detection mode, which has been validated by experimental assessment.

On the generation and identification of traveling waves in non-circular structures - application to innovative piezoelectric motors

We have been developing new concepts of linear and circular ultrasonic actuators using traveling waves in rectangular or square structures, which are adapted to batch micro-machining of silicon. The first prototypes we built were all clamped and used a simple combination of modes allowing movement transmission through one contact point. Yet, in order to increase the efficiency of our motors, we consider using new combinations of modes with higher ranks (and then more contact points) and also other boundary conditions. As it is not easy to predict if an accurate quasi-traveling wave can be generated in a given structure and with a given contribution of modes, we have developed a simulation program using MAPLE software. This program uses successive criteria to select the zones where the traveling wave can be found, according to computer parameters. In this paper, we present the different steps used to check the possibility of realizing an actuator with a given configuration in any type of structure. We illustrate this with simple theoretical examples using several structures with different boundary conditions and finally we give some experimental results obtained with a circular motor using a more complex combination of modes.

Linear motor using a quasi-travelling wave in a rectangular plate

Abstract Usually, ultrasonic motors generate a rotating movement, particularly motors using a travelling wave. Due to axial symmetry, production of this type of wave in a circular shape is easier than in others shapes. In this paper, we show that it is possible to generate a linear movement using a quasi-travelling wave in a rectangular plate. If the dimensions of the plate are well adjusted, the combination of two resonant modes, for example 2-1 and 1–3 modes, which have the same frequency, will, with suitable excitation, produce a quasi-travelling wave. A linear motor using a rectangular plate has been made to demonstrate the principle. This type of actuator will of course present the same advantages as in the usual travelling wave ultrasonic motors. In addition, the use of rectangular shapes is suitable for miniaturisation, for example, in the case of chemically etched silicon membranes.

Improving immunosensor performances using an acoustic mixer on droplet microarray

A major drawback of protein microarrays is the lack of control of ligand immobilization at the surface of the chip which limits their performances and thus their impacts in in vitro diagnosis. To improve antibody (Ab) grafting during the spotting process on commercialized gold SPRi chips, we propose to produce a chaotic flow in every spotted droplet, by using an acoustic field, in order to disrupt the steady state of the reaction of Ab grafting. Our results show that acoustic mixing during Ab binding at the biochips surface increases their biorecognition performances of a mean factor of 2.7 in comparison with Ab layer grafted in a passive mode. Moreover, it increases statistically the homogeneity of the response over all the surface of the chips.

Temperature compensation of lamb wave sensor by combined antisymmetric mode and symmetric mode

Both thermal sensitivity and mass sensitivity in liquid of the first antisymmetric (A0) mode and the first symmetric (S0) mode of Lamb wave biosensor were investigated. A0 and S0 modes are sensitive to the mass change on the surface of the sensor but A0 mode is also sensitive to the liquid in the region of evanescent wave associated with Lamb wave. By combining A0 mode and S0 mode, the measurement error due to the environmental temperature drift decreased by a large factor, therefore, the environmental temperature was efficiently compensated without changing the structure of Lamb wave sensor.

Micropositioning and Fast Transport Using a Contactless Micro-Conveyor

Guillaume J. Laurent *, Anne Delettre, Rabah Zeggari, Reda Yahiaoui, Jean-Franc¸ois Manceauand Nadine Le Fort-PiatFEMTO-ST Institute, UFC-ENSMM-UTBM-CNRS, Universite de Franche-Comt´ e,´Besanc¸on 25000, France; E-Mails: anne.delettre@femto-st.fr (A.D.); rabah.zeggari@femto-st.fr (R.Z.);reda.yahiaoui@femto-st.fr (R.Y.); jfmanceau@femto-st.fr (J.-F.M.); nadine.piat@ens2m.fr (N.L.F.-P.)* Author to whom correspondence should be addressed; E-Mail: guillaume.laurent@ens2m.fr;Tel.: +33-3-8140-2808; Fax: +33-3-8140-2809.Received: 28 November 2013; in revised form: 16 December 2013 / Accepted: 6 February 2014 /Published: 12 February 2014Abstract: The micro-conveyor is a 9 9 mm

A Multi-Parameter Decoupling Method with a Lamb Wave Sensor for Improving the Selectivity of Label-Free Liquid Detection

The anti-symmetric modes (A01 mode for low frequency, A03 mode for high frequency) and symmetric modes (S0 mode) produced by Lamb wave sensor are used to detect multi-parameters of a liquid, such as its density, sound velocity and viscosity. These modes are found to be very different to the parameters. For example, the A01 mode is very sensitive to the liquids density but the A03 mode is sensitive to its sound velocity. The measurements of the attenuation with S0 mode can give out liquids viscosity after its density been determined by A01 mode. That could be a way to distinguish an unknown liquid with high sensitivity or to solve the problem of the selectivity of label free detection on biosensors.

Influence of gases on Lamb waves propagations in resonator

We investigate gases effects on the Lamb wave resonant modes. Various frequency ranges are studied for the antisymmetric mode considering wave velocities either higher or lower than the gas sound velocity. We observe that the relative frequency shifts in the low frequency range of the antisymmetric mode is rather important; in the high frequency range of this mode, the quality factor decreases quickly when the Lamb wave phase velocity approaches the gas sound velocity. We find a good agreement between calculations and experiments in air and helium. The results suggest the possibility to get aerodynamics parameters of gas flow.

Measurements of evanescent wave in a sandwich Lamb wave sensor

One method for evanescent wave measurement of the Lamb wave biosensor is proposed by putting another Lamb wave device above the first with the distance less than the evanescent field penetration depth in the liquid. The liquid layer is sandwiched with the two Lamb wave devices. The devices are interacted by an evanescent field; thus the evanescent wave can be studied. The mode is split by the interaction of the evanescent wave. The investigation of the evanescent field gives insight into acoustic biosensors and provides precise and multiparameter measurements

Droplet ejector using surface acoustic waves

The present study aims to investigate droplet ejection using Surface Acoustic Waves (SAW). The interests in droplet ejection microsystems have dramatically grown in recent years due to inkjet printhead demand (Drop-On-Demand). Among several actuating methods (thermal, piezoelectric, etc.), the thermally driven inkjet printhead is the most successful (low cost, easy fabrication and high printing quality). Almost all of the current ink jet printers eject ink droplets through nozzles, with a direction of ejection always perpendicular to the nozzle surface. Surface acoustic waves devices are widely used for frequency filtering and are mainly devoted to cellular phones and telecommunication handset. Nowadays, recently published works have demonstrated the interest of SAW for guiding and positioning small liquid droplet atop a flat surface. This paper describes a new way to eject droplets (water, ink, etc...) using SAW. The surface acoustic waves devices used to eject droplets are carried out on lithium niobate substrates (LiNbO3 cut Y+128°, X propagation). The Rayleigh waves are excited using classical inter-digital transducers (IDT). The design of IDT has been simulated with finite element analysis and boundary element methods. The computations on the design of the IDT have been compared with measurements. The vibration amplitude of the wave necessary to droplet ejection is measured using a heterodyne laser probe. The range of the droplets volume ejected is between 100nl and 1μl. The influence of the supply voltage on the ejection is described.