LiNbO3 Piezoelectric Substrate Research Articles

A traveling surface acoustic wave-based micropiezoactuator: A tool for additive- and label-free cell lysis.

We propose a traveling surface acoustic wave (TSAW)-based microfluidic method for cell lysis that enables lysis of any biological entity, without the need for additional additives. Lysis of cells in the sample solution flowing through a poly (dimethyl siloxane) microchannel is enabled by the interaction of cells with TSAWs propagated from gold interdigitated transducers (IDTs) patterned onto a LiNbO3 piezoelectric substrate, onto which the microchannel was also bonded. Numerical simulations to determine the wave propagation intensities with varying parameters including IDT design, supply voltage, and distance of the channel from the IDT were performed. Experiments were then used to validate the simulations and the best lysis parameters were used to maximize the nucleic acid/protein extraction efficiency (>95%) within few seconds. A comparative analysis of our method with traditional chemical, physical and thermal, as well as the current microfluidic methods for lysis demonstrates the superiority of our method. Our lysis strategy can hence be used independently and/or integrated with other nucleic acid-based technologies or point-of-care devices for the lysis of any pathogen (Gram positives and negatives), eukaryotic cells, and tissues at low voltage (3 V) and frequency (33.17 MHz), without the use of amplifiers.

Coherent surface acoustic wave–spin wave interactions detected by micro-focused Brillouin light scattering spectroscopy

We investigated the interaction of surface acoustic waves and spin waves with spatial resolution by micro-focused Brillouin light scattering spectroscopy in a Co40Fe40B20(10 nm) ferromagnetic layer on a LiNbO3-piezoelectric substrate. We experimentally demonstrate that the magnetoelastic excitation of magnons by phonons is coherent by studying the interference of light scattered off generated magnons and annihilated phonons. We find a pronounced spatial dependence of the phonon annihilation and magnon excitation, which we map as a function of the magnetic field. The coupling efficiency of the surface acoustic waves (SAWs) and the spin waves is characterized by a magnetic field-dependent decay of the SAWs amplitude.

Plasmas and acoustic waves to pattern the nanostructure and chemistry of thin films

In this work, piezoelectric AWs and plasmas have been brought together during the growth of a thin film as a novel methodology of plasma-assisted thin film structuration. The ensuing effects have been investigated on a model system where SiO2 and SiOx (x<2) thin films have been deposited by magnetron sputtering at oblique angles (MS-OAD) on an electro-acoustically excited LiNbO3 piezoelectric substrate under resonant conditions. The microstructure of the resulting films was 2D patterned and depicted submillimeter size intermingled zones with different optical characteristics, compositions (SiO2 and SiOx) and porosity, from highly porous to dense and compact regions. The 2D nanostructural pattern mimics the AW distribution and has been accounted for by means of a specific simulation model. It is concluded that the morphological and chemical film pattern replicates the distribution of polarization potential on the surface of the AW activated substrate immersed in the plasma. Moreover, we show that the main mechanism responsible for the appearance of domains with different morphology and chemical composition is the focused impingement of Ar+plasma ions on certain regions of the substrate. The general character of this patterning process, the underlying physics and its possibilities to tailor the composition and microstructure of dielectric thin film materials are discussed.

Acousto-electric measurements at 2.5 GHz on graphene transferred onto YX128°-LiNbO3

Surface acoustic wave delay lines with an operational frequency of 2.5 GHz have been designed to measure the acousto-electric transport of carriers in graphene transferred onto YX128°-LiNbO3 piezoelectric substrate. The monolayer of graphene on LiNbO3 presented sheet resistance in the range of 733–1230 Ω/□ and ohmic contact resistance with gold of 1880 to 5200 Ωμm. The measurements with different interaction lengths on graphene bars have allowed the extraction of carrier absorption and mobility parameters from acousto-electric current. Graphene presented higher acousto-electronic interaction in the GHz range than previously reported values in the range of 100s MHz with carrier absorption losses of 109 m−1 and mobility for acoustically generated charges of 101 cm2V−1s−1.

Droplets transport together with a small steel ball driven by surface acoustic waves

A new method for transporting microfluid was presented. An interdigital transducer was fabricated on an YX-128° LiNbO3 piezoelectric substrate for generating surface acoustic wave (SAW). A sample droplet is placed on a small steel ball, which is driven by the SAW. Temperature characteristics of the sample droplet are theoretically analyzed, and experimentally verified. Red ink solution is demonstrated for sample droplet transport. The presented transport method is successfully applied in color development reaction. Compared to traditional SAW driving droplets, the equilibrium temperature of sample droplet driven by presented method is decreased 11.8 °C at 30.9 dBm of electrical signal power.

Simulating the piezoelectric substrate influence on the characteristics of surface acoustic wave-magnetostriction sensor based on the FeNi magnetic sensitive material

This paper simulates the influence of two piezoelectric substrate types on the sensitivity and measuring range of surface acoustic wave-magnetostriction (SAW-MO) sensor by the finite elements method (FEM) based on using the FeNi magnetic sensitive layer with E-H chacrateristics (Young’s Modulus – Magnetic field intensity). The sensor structure selected for the study is the delay-line: the distance between the two sets of electrodes is 5mm, the number of finger pairs of each electrode set is 25, and the distance-width between the fingers is 10m regularly, the electrode material is aluminum. The piezoelectric substrates chosen for simulation are LiNbO3 and AlN in which the LiNBO3 piezoelectric substrate is the block form with the surface velocity of 3318.1m/s and the AlN piezoelectric substrate is the thin film with the surface wave velocity of 5598.9m/s. So the generality is ensured when evaluating their influence on the response of SAW-MO sensor. For magnetic sensitive materials, the group selected the FeNi which E-H characteristics was experimentally built. During simulation by finite elements method, the sensor structure is tested with many datasets whose number of divided elements is different. However, the simulation results have converged with the number of divided elements is 113556. The simulation result shows that the sensivity of the FeNi/IDT/AlN structure magnetic sensor is larger than the FeNi/IDT/LiNbO3 structure magnetic sensor with sensitivities of 8.698kHz/Oe and 2.345kHz/Oe, respectively. The result also indicates that the response range of the FeNi/IDT/AlN magnetic sensor is [0 ÷ 109]Oe, which is smaller than the FeNi/IDT/LiNbO3 magnetic sensor is [0 ÷ 190]Oe.

Design Performance and Frequency Response Analysis of SAW-Based Sensor for Dichloromethane Gas Sensing Amidst the COVID-19

BackgroundTo avoid the risk of increase in the rate of human infection is a big challenge for healthcare staffs during the treatment of patients affected from corona virus disease-2019 (COVID-19). This work is intended to save COVID-19-infected patients from conveyed hazardous volatile gases (VOCs) by the gas stream. The VOCs are generally generated from the pathways of medical respiratory devices.MethodHere, we present a surface acoustic wave-based sensor device for sensing dichloromethane (DCM) gas that can be connected with a gas pathway system used in medical devices. Dichloromethane is a volatile organic compound. Single- (polyisobutylene, PIB) and multi- (polyisobutylene/silicon nitride, PIB/Si3N4) surface acoustic wave-based sensors are designed on LiNbO3 piezoelectric substrate. The designed models patterned with interdigitated transducer (IDT) aluminum (Al) electrodes are used to analyze gas sensing behavior for dichloromethane (CH2Cl2, DCM) gas.ResultsThe studies for DCM gas sensing are carried out for single- and multi-layer models using COMSOL Multi-physics software. The resonant frequency and displacement are also observed for 100 ppm gas concentration of DCM at room temperature. It has been found that multi-layer designed model shows higher sensitivity as compared to single layer (PIB/LiNbO3) model on exposing DCM gas.ConclusionThe estimation of various parameters observed by the proposed module is also explained. It is observed that the sensitivity of sensor for detection of VOCs (generated in gas pathways in medical devices) is best suited in the present crisis of COVID-19 pandemic.

Transporting droplets by help of a medium on a piezoelectric substrate

A new method for transporting droplets is presented to avoid directive radiation of surface acoustic wave (SAW). An interdigital transducer (IDT) is fabricated on a 128°-YX LiNbO3 piezoelectric substrate using microelectric technology. A droplet to be transported is placed on a steel ball, which is driven by SAW. The droplet on the steel ball is then transported together with the steel ball. 0.5ul red ink solution was successfully transported by help of the steel ball with 2 mm diameters at 30.9 dBm electric signal power. Color development reaction is also implemented by transporting reaction solution using presented method to a paper-based device.

The spatial transportation of a droplet along a spherical surface based on surface acoustic wave

A method for spatial transportation of a droplet was presented. Spatial transporting characteristic was theoretically analyzed. The droplet on an YX-128° LiNbO3 piezoelectric substrate was exerted the acoustic streaming force and resistance from a steel ball with 2 mm diameter, which was fixed on the piezoelectric substrate by help of polydimethylsiloxane (PDMS). The droplet was then transported along the spherical surface. Experimental results show that spatial transportation height is relied on the size of the droplet and the power of an electric signal. 1.5 µl red ink droplet can be transported to the ball top at 30.8 dBm electric signal power.

A paper-based microfluidic device integrated into a piezoelectric substrate

A novel, simple and low-cost method for fabricating paper-based microfluidic device was presented. A soldering wire was used for making a template with specific pattern, and transfer printing to a filter paper by help of polydimethylsiloxane (PDMS). The device was mounted on an YX-128° LiNbO3 piezoelectric substrate. The entire fabrication process could be finished less than one minute without using any complicated equipments. Important parameter in the fabrication of paper-based microfluidic device such as transfer printing time was discussed. To verify the function of the paper-based microfluidic device, color development reactions of starch were implemented.

The climbing characteristics of micro fluid on a piezoelectric substrate

The climbing phenomenon of fluid driven by surface acoustic wave was discovered, and its climbing characteristic was experimentally studied. A steel ball was fixed on an YX-128° LiNbO3 piezoelectric substrate by help of polydimethylsiloxane at the bottom of the steel ball. The fluid was forced by the acoustic streaming force and the resistance from the steel ball, leading to climbing the steel ball. The climbing characteristic was investigated using red ink solution. Results show that 3 µL red ink solution can climb the top of the steel ball with 2 mm diameter at 28.7 dBm electric signal power.

Design and Implementation of 2.45 GHz Passive SAW Temperature Sensors with BPSK Coded RFID Configuration.

A surface acoustic wave based passive temperature sensor capable of multiple access is investigated. Binary Phase Shift Keying (BPSK) codes of eight chips were implemented using a reflective delay line scheme on a Y-Z LiNbO3 piezoelectric substrate. An accurate simulation based on the combined finite- and boundary element method (FEM/BEM) was performed in order to determine the optimum design parameters. The scaling factor ‘s’ and time delay factor ‘τ’ were extracted using signal processing techniques based on the wavelet transform of the correlation function, and then evaluated at various ambient temperatures. The scaling factor ‘s’ gave a more stable and reliable response to temperature than the time delay factor ‘τ’. Preliminary results show that the sensor response is fast and consistent subject to ambient temperature and it exhibits good linearity of 0.9992 with temperature varying from 0 to 130 °C.

A new microvalve controlled by surface acoustic wave

ABSTRACTA new microvalve controlled by surface acoustic wave was presented. A shape memory alloy (SMA) with plastic sheet was integrated into a printed circuit board by way of small copper pipe. A 128°-YX LiNbO3 piezoelectric substrate was under the SMA wire with small gap. A polydimethylsiloxane (PDMS) microchannel was squeezed by the extension of the heated SMA wire due to surface acoustic wave radiation. The microvalve state was then changed. Experimental results show that the switching-off time of the microvalve is 39.533 s at 28.5 dBm electric signal power. The variation of SMA size during expansion is theoretically calculated.

Highly sensitive BEHP-co-MEH:PPV + Poly(acrylic acid) partial sodium salt based relative humidity sensor

A high performance humidity sensor for environmental and health monitoring has been fabricated using a composite of BEHP-co-MEH:PPV co-polymer and super hydrophilic Poly(acrylic acid) partial sodium salt (PAASS) as the sensing layer. The device was fabricated using all printing methods. Reverse offset printing was used to fabricate silver electrodes on LiNbO3 piezoelectric substrate while spin coating was used to deposit the composite active layer. Four samples with different concentrations of PAASS were fabricated to find out the effect of super hydrophilic material concentration on the performance of the sensors. Physical, chemical, and electrical characterizations were performed for the sensors and their response was recorded for varying humidity levels. The results showed that the response of sensors towards humidity change is very sensitive, quite stable, and can effectively measure low humidity levels with reasonable response and recovery times. The capacitance of the sensors was measured between 0% RH and 80% RH at 1kHz and 10kHz test frequencies. The maximum absolute change in capacitance was ∼2750pF (34pF per%RH sensitivity) for the sample with maximum concentration of PAAPSS recorded at 1kHz test frequency. Different composition ratios resulted in different performance parameters, with some of them improved, and the others compromised. The concentrations can be optimized with application specific requirements.

Controlled rotation and translation of spherical particles or living cells by surface acoustic waves.

We show experimental evidence of the acoustically-assisted micromanipulation of small objects like solid particles or blood cells, combining rotation and translation, using high frequency surface acoustic waves. This was obtained from the leakage in a microfluidic channel of two standing waves arranged perpendicularly in a LiNbO3 piezoelectric substrate working at 36.3 MHz. By controlling the phase lag between the emitters, we could, in addition to translation, generate a swirling motion of the emitting surface which, in turn, led to the rapid rotation of spherical polystyrene Janus beads suspended in the channel and of human red and white blood cells up to several rounds per second. We show that these revolution velocities are compatible with a torque caused by the acoustic streaming that develops at the particles surface, like that first described by [F. Busse et al., J. Acoust. Soc. Am., 1981, 69(6), 1634-1638]. This device, based on standard interdigitated transducers (IDTs) adjusted to emit at equal frequencies, opens a way to a large range of applications since it allows the simultaneous control of the translation and rotation of hard objects, as well as the investigation of the response of cells to shear stress.

Enhanced sensitivity of temperature-compensated SAW-based current sensor using the magnetostrictive effect

A temperature-compensated surface acoustic wave (SAW)-based current sensor was proposed in this contribution, composed of a sensor chip made by SAW delay line patterns on a SiO2/128° YX LiNbO3 piezoelectric substrate, a magnetostrictive FeCo film deposited on the SAW propagation path, and a corresponding differential oscillation configuration. The FeCo coating produced magnetostrictive strain under the magnetic field generated by the applied current, leading to linearity changes in the SAW propagation in the form of velocity change. The corresponding differential oscillation frequency shift was used to evaluate the tested current. By solving the coupled electromechanical field equation in a layered structure while considering the magnetostrictive effect, the optimal FeCo film thickness, and sensor operation frequency yielding high current sensitivity, were determined, and then confirmed experimentally by evaluating the developed SAW current sensor system utilizing a Helmholtz coil. A high sensitivity of 16.6 KHz A−1 (8.3 KHz m−1 T−1), excellent linearity, and lower detection limit (∼0.2 mA) were achieved with our 300 MHz SAW sensor with a 500 nm FeCo coating and aspect ratio of 2:1.

The investigation of hydrogen gas sensing properties of SAW gas sensor based on palladium surface modified SnO2 thin film

The sol-gel method and the magnetron sputtering method were used to deposit the SnO2 thin films on 128° YX LiNbO3 piezoelectric substrate for fabricating different kinds of delay-line surface acoustic wave (SAW) hydrogen gas sensors. To improve hydrogen gas sensing performance of SnO2 sensing films, the bi-layer structure sensitive films was used, which was composed of one pure SnO2 layer and one highly dispersed palladium nanoparticle layer. This bi-layer structure evidently enhanced the hydrogen gas sensing properties of SnO2 thin films. The microstructure, surface morphology and composition of as-prepared SnO2 sensitive films were analyzed by XRD, FESEM and XPS. The oscillator circuit with SAW sensor as resonate was designed to transduce the response of sensitive film into the frequency shift of oscillator. One precise temperature control system was used to ensure the temperature stability of SAW device. The Pd-surfaced-modified SnO2 thin film deposited by magnetron sputtering method has the highest frequency shift of 115.9kHz to 2000ppm hydrogen gas at 175°C. The influence of thickness on the morphology of Pd nanoparticles and hydrogen gas sensing performance was studied. The size of Pd nanoparticle increases with thickness of Pd films and too thick Pd layer will reduce the hydrogen gas sensing performance of SnO2 films.

Design and Development of ZnO Based Gas Sensor for Fruit Ripening Detection

This work focuses on the nondestructive fruit ripeness detection system at different maturity stages. The study involved a computational approach whereby the detector is simulated and characterized. The development of the 2 dimensional finite elements provides deeper understanding in an isotropic media of the sensor. The paper presents a sensitive layer of the zinc oxide with a thickness of 0.5 μm on LiNbO3 piezoelectric substrate for ethylene (C2H4) gas sensing application in order to distinguish maturity level of fruits. In addition the sensor acts as a better device for sensing the amount of ethylene gases that releases from mature fruits.

Development of a Wireless and Passive SAW-Based Chemical Sensor for Organophosphorous Compound Detection.

A new wireless and passive surface acoustic wave (SAW)-based chemical sensor for organophosphorous compound (OC) detection is presented. A 434 MHz reflective delay line configuration composed by single phase unidirectional transducers (SPUDTs) and three shorted reflectors was fabricated on YZ LiNbO3 piezoelectric substrate as the sensor element. A thin fluoroalcoholpolysiloxane (SXFA) film acted as the sensitive interface deposited onto the SAW propagation path between the second and last reflectors of the SAW device. The first reflector was used for the temperature compensation utilizing the difference method. The adsorption between the SXFA and OC molecules modulates the SAW propagation, especially for the time delay of the SAW, hence, the phase shifts of the reflection peaks from the corresponding reflectors can be used to characterize the target OC. Prior to the sensor fabrication, the coupling of modes (COM) and perturbation theory were utilized to predict the SAW device performance and the gas adsorption. Referring to a frequency-modulated continuous wave (FMCW)-based reader unit, the developed SAW chemical sensor was wirelessly characterized in gas exposure experiments for dimethylmethylphosphonate (DMMP) detection. Sensor performance parameters such as phase sensitivity, repeatability, linearity, and temperature compensation were evaluated experimentally.

Acoustic wave based biosensor to study electroacoustic based detection of progressive (SW-48) colon cancer cells from primary (HT-29) cells

A travelling surface acoustic wave (TSAW) biosensor on a LiNbO3 piezoelectric substrate is designed and fabricated to study the proliferation of HT-29 and SW-48 cancer cells. The device integrates double interdigital transducers (IDTs) in which the travelling SAW (TSAW) is operating at around 10.3-MHz-centered medical band. The experiments were carried out using label free method, with and without the presence of cell media culture, primary (HT-29) and progressive (SW-48) colon cancer cells. It was noted that at the presence of cancer cells, the sensor response was considerably altered, mostly due to the electroacoustic effect. However, presence of the culture media solution did not have a considerable impact on the frequency response of the biosensors in respect to cells attachment situation. The resonance peaks at the presence of HT-29 cells had fewer shifts toward lower frequencies, compared to SW-48 cells, because of the lower amount of negative electrical charges acquired over the membrane of HT-29 cells. Finite-element analysis (FEA) using COMSOL Multiphysics® software package is carried out. The numerical results are in good agreement with the experimental ones. It is suggested that using the proposed biosensor is a promising path to detect the proliferation of cancer cells.