Microfluidic Sensor based on ALN Vertical SAW structure: Investigation, Design and Simulation

VIETNAM NATIONAL UNIVERSITY, HANOI UNIVERSIRY OF ENGINEERING AND TECHNOLOGY - - BUI THU HANG MICROFLUIDIC SENSOR BASED ON ALN VERTICAL SAW STRUCTURE: INVESTIGATION, DESIGN AND SIMULATION MASTER THESIS in ELECTRONICS AND TELECOMMUNICATIONS TECHNOLOGY Hanoi – 2013 - - BÙ Ê B Ứ , Ằ Ế KẾ V M ẢM B Ế V LỎ S W Ứ L Ậ VĂ P Ỏ Ó Ấ Ê VẬ L SĨ l Ử-V Ễ ội – 2013 Ú Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation TABLE OF CONTENT GLOSSARY ACKOWNLEDGEMENTS LISTS OF TABLES LISTS OF FIGURES Chapter Introduction 1.1 Motivation and Objectives 1.2 Organization of Thesis Chapter Theoretical Analysis of the AlN-based Microfluidic Sensor 12 2.1 Introduction 12 2.2 Surface Acoustic Waves 13 2.2.1 Shear Horizontal Surface Acoustic Waves (SH-SAWs) 13 2.2.2 Rayleigh Surface Acoustic Waves (R-SAWs) 14 2.3 Propagation of Acoustic Waves in contact with a Liquid Medium 16 2.3.1 Boundary Conditions 19 2.3.2 Standing and Linear Motion Medium 19 2.3.3 Moving Liquid Medium 20 2.4 Equivalent Circuit Model of SAW Devices 21 2.4.1 Model Implementation 21 2.4.2 Frequency Response 22 2.4.3 Attenuation 22 2.5 Conclusion 23 Chapter 3-D Design of AlN-based Microfluidic Sensor 24 3.1 General Description 24 3.2 Design Principles 25 3.3 FEM Simulation for AlN-based Microfluidic Sensor 29 3.3.1 General Configuration 29 3.3.2 Lithium Niobate 30 3.3.3 Aluminium Nitride 33 Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation 3.4 Masks designed 35 Chapter Results and Discussion 38 4.1 General Description 38 4.2 Density and viscosity 38 4.2.1 Lithium Niobate Crystal 38 4.2.2 Aluminium Nitride Crystal 43 4.3 Sensing Liquid Status 45 4.3.1 Constant Velocity 45 4.3.2 Non-constant Velocity 49 4.4 Conclusion 53 Chapter Conclusions and Future Work 54 5.1 Conclusions 54 5.2 Future work 54 Reference 56 Appendix: Material Parameters for Piezoelectric Substrate 59 A Lithium Niobate 59 B Aluminium Nitride 59 Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation LOSS Y IDT InterDigital Transducer SAW Surface Acoustic Wave R-SAW Rayleigh Surface Acoustic Wave SH-SAW Shear-Horizontal Surface Acoustic Wave LiNbO3 Lithium Niobate Mo Molybdenum Al Aluminium AlN Aluminium Nitride Si Silicon SOI Silicon On Insulator Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation KOW LED EME S I would like to sincerely thank my advisor, Assoc Prof Chu Duc Trinh for their encouragement, guidance, and invaluable supports throughout the course of this study He guided me in studying microfluidics and always gave me meaningful and profound explanations I would like to gratefully acknowledge Dr Tran Duc Tan and Assoc Prof Rusu Vasile Catelin for useful suggestions in my dissertation Their guidance enabled me to complete my thesis work I am also highly thankful to all teachers at Dept of Electronics and Telecommunications for supports and encouragement Many thanks to staff in department for their helps of thesis defence procedures Finally, it is my profound gratitude to my family, especially my mom, my cousin Phan Quoc Vi for their moral supports and encouragement in my life Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation L S S OF BLES Table 3.1: Physical properties of the chosen liquids 33 Table 3.2: Parameters of SAW device based on Aluminium Nitride Crystal .34 Table 3.3: Design parameters of AlN-based SAW device 34 Table 3.4: The design parameters for AlN-based microfluidic sensor with single channel 36 Table 3.5: The design parameters for AlN-based microfluidic sensor with multichannel 36 Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation L S S OF F ES Figure 1.1: The flow chart for the development process of an AlN-based Microfluidic Sensor prototype .10 Figure 2.1: Acoustic wave propagation direction in a Cartesian coordinate system .13 Figure 2.2: (a) The typical SH-SAW structure (b) Illustration of shear horizontal (SH) polarized displacement 14 Figure 2.3: (a) Schematic of the particle motion for a Rayleigh wave (b) Ultrasonic radiation into water by SAW when sensing channel placed on substrate .15 Figure 2.4: (a) The simple SAW structure for sensing liquid (b) Ultrasonic radiation into water when sensing channel is placed along the vertical axis of device 16 Figure 2.5: Principle construction of multilayer SAW sensor .17 Figure 2.6: Geometry of the problem for analysing propagation of Rayleigh waves .18 Figure 2.7: Mason equivalent circuit model 21 Figure 3.1: Schematic drawing of the integrated inkjet system 26 Figure 3.2: Top and cross-view of one-channel microfluidic sensor 27 Figure 3.3: Top and cross-view of two-channel microfluidic sensor 28 Figure 3.4: Top and cross-view of one-input two-channel microfluidic sensor 28 Figure 3.5: Top and cross-view of multi-output microfluidic sensor 29 Figure 3.6: Schematic illustration of two-channel R-SAW sensor and liquid well position 30 Figure 3.7: Design parameters of Channel and well size .31 Figure 3.8: Meshed image of 3D SAW model with the well in the middle of the wave propagation path 32 Figure 3.9: General view for all devices in one die .35 Figure 4.1: Total displacement of corresponding points in Channel and Channel with different well diameters 39 Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.2: Total displacement of the well behind points with three liquid types .40 Figure 4.3: Output voltage of Group from the 3-D SAW model with and without deposited well from to 130 nsec 41 Figure 4.4: Output voltage of Group from the 3-D SAW model with and without deposited well from to 130 nsec 43 Figure 4.5: (a) Total displacement envelops of points placed behind the well .43 Figure 4.6: Electrical attenuation response (shown as insertion loss) for the SAW device 44 Figure 4.7: The time delay of system with the well having liquid density =1, 3, 6, and 12 g/cm3 44 Figure 4.8: Potential amplitude at center frequency on the IDT receiver for linear group 45 Figure 4.9: Ratio coefficient of displacement amplitudes before and after the well for linear group .46 Figure 4.10: (a) Delay time and (b) Velocity decay coefficient when liquid moves linearly 47 Figure 4.11: Attenuation corresponding to linear motion function .48 Figure 4.12: Effect of SAWs on linear fluid flow 49 Figure 4.13: Potential amplitude at center frequency on the IDT receiver for exponential motion group 50 Figure 4.14: Ratio coefficient of displacement amplitudes before and after the well for exponential motion group .50 Figure 4.15: Velocity decay for exponential motion group 51 Figure 4.16: Delay time when liquid moves nonlinearly .51 Figure 4.17: Attenuation corresponding to exponential motion function 52 Figure 4.18: Effect of SAWs on exponential fluid flow 52 Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Chapter ntroduction 1.1 Motivation and Objectives In recent years, microfluidic technology received a lot of attention because its widespread applications in printing, biomedicine Device integration and miniaturization based on microfluidic technology has been growing up quickly In addition, expected devices may have advantages such as: small size, facile usage and low cost, fast detection speed, high accuracy, less consumption power and high integration capability One of the present microfluidic technologies utilizes surface acoustic wave (SAW) [1][2] It is well-known owing to applications such as actuators, antennas and driven droplet manipulation using SAW atomization and jetting technique [3][4][5] SAW devices are also widely utilized in sensors [6] Such devices convert electrical energy into mechanical energy and vice versa Specifically, when the transformation from electrical to mechanical energy occurs at the InterDigital Transducder (IDT) transmitter, acoustic waves travel through the surface SAW waves include Rayleigh waves, and sliding shear waves The amplitude of the Rayleigh-SAWs of around 10Å is very small and exponentially declines Because wave penetration into the substrate is inversely proportional to frequency, in order to limit reflections and refractions at the bottom, the material size is large enough This mechanical vibration on the surface continues until opposite transform process at the IDT receiver Waves that not retransform electrical energy at the receiver are absorbed by wax, polyimide placed before and after the input and output IDT Sensing mechanism is electrical perturbation on the IDT receiver due to obstacles on the propagation path or even if R-SAWs travel through the different media [7] Prominent advantages of SAW devices are micro derivation size for fluid, high sensitivity and fabrication ability on compatible material The structure trend is vertical sensing channel This suggests the requirement of the vertical SAW sensor Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.9 displays the ratio coefficient equation m of the weight of the X-axis and Z-axis as a function of one over the square root of the velocity Ω Comparing simulations with analytical derivations, we find that the curve approaches the abscissa axis when velocity comes to infinite value Figure 4.9: Ratio coefficient of displacement amplitudes before and after the well for linear group As the liquid is present in the well, it drives to delay time due to acoustic wave changes, distortion such as phase and velocity shift, velocity degradation or even velocity excitation The delay time of a linearly moving liquid is shown in Figure 4.10a It indicates that it is excited due mainly to there is fluid motion along Z axis in the well The results suggest that velocity within a range of 10 to 90 mm/s essentially affects excepting 30 mm/s and that of 60 mm/s reaches a peak Meaning velocity decay achieves the saturated state when increasing the velocity (see Figure 4.10b) Bui Thu Hang Page 46 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.10: (a) Delay time and (b) Velocity decay coefficient when liquid moves linearly Bui Thu Hang Page 47 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.11: Attenuation corresponding to linear motion function For the reciprocal and symmetric model for two sets of IDTs, the reflection coefficient S21 of the sensor which is the same magnitude as the return loss S12 is calculated by IL = 20log10|Vout/Vin| [dB] [26] As shown in Figure 4.11, the insertion loss spectra of the multilayer SAW device shows that resonant frequency is found from approximately 1.49 to 1.52 GHz which corresponds to different liquid velocities from 10 to 80 mm/s in the well As the material velocity is affected, the output signal at the IDT receiver is also degraded by the liquid state in the well, especially at = 60 mm/s Theoretically, the acceleration of the linear motion group is zero Velocity reaches stable zero-state after 30 ns as shown in Figure 4.12 Therefore, although acoustic waves have an effect on the liquid velocity in the well, they not cause much distortion in the liquid Bui Thu Hang Page 48 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.12: Effect of SAWs on linear fluid flow 4.3.2 Non-constant Velocity The dependency of the decay constant bf and the acoustic wave velocity v on the fluid motion ( ) ( ) leads to a distortion of the output potential in the IDT receiver, compressional and shear horizontal waves Therefore, it is hard to find the law governing the potential amplitude Potential amplitudes of exponential velocity functions at center frequency are equal as shown in Figure 4.13 When overcoming the well, the acoustic wave is excited by liquid streaming It is clearly seen that the excitation of the shear horizontal wave is more than that of the compressional wave and their ratio coefficient grows linearly in Figure 4.14 Figure 4.15 describes the piezoelectric velocity decay of acoustic wave after the well As there appears the leaky acoustic wave in the well, it causes material velocity attenuation The trend of velocity decay coefficient is irregularly downward Bui Thu Hang Page 49 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.13: Potential amplitude at center frequency on the IDT receiver for exponential motion group Figure 4.14: Ratio coefficient of displacement amplitudes before and after the well for exponential motion group Bui Thu Hang Page 50 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 4.15: Velocity decay for exponential motion group The result in Figure 4.16 reveals that compared to the output signal where there is no motion the well, delay times of all liquid velocities in the high order functions are later than that of the standing liquid in the well Figure 4.16: Delay time when liquid moves nonlinearly The electrical attenuation is shown as insertion loss of the frequency response in Figure 4.17 Because the velocity decay coefficient of the standing liquid is smallest, its attenuation achieves the lowest value At t and t6 mm/s, the attenuation Bui Thu Hang Page 51 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation reaches the highest value Like the linear group, with the constant velocity, it attains saturation after a short time (Figure 4.18) The simulation results also indicate that the higher the velocity is, the faster its stability becomes Figure 4.17: Attenuation corresponding to exponential motion function Figure 4.18: Effect of SAWs on exponential fluid flow Consequently, different liquid situations in the well bring in attenuations for the acoustic waves on the piezoelectric substrate On the other hand, fluid motion plays as a role in interference and causes changes on the IDT receiver Bui Thu Hang Page 52 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation 4.4 Conclusion The 3-D finite element model of microfluidic sensor with two channels demonstrates that it is suitable for liquid sensing According to the vertical sensing area, although leaky Rayleigh waves generated on the boundary between liquid and SAW surface exist, the attenuation is not significant and the received signal on the output IDTs is still large enough Simulation results using LiNbO3 and AlN crystals show how fluid density has a high impact on delay time and insertion loss while viscosity has a limited one Also, this work reveals not only relation between the displacement magnitude along the X-axis and Z-axis, but also the output potential While this ratio is a function of one over square root of velocity Ω for the constant velocity case, it is a linear function for the exponential motion group It demonstrates the stability of the potential when the liquid moves linearly in the well whereas it is not really steady for exponential motion case The constant velocity group demonstrates that when velocity goes up, its decay constant achieves a saturated state while it decidedly decreases downward in the exponential motion group As there appears both excitation and reduction of some components in SAWs, attenuation of motional liquid is still more than that of stationary liquid However, the fluid motion in the well is influenced insignificantly by surface acoustic waves on the Aluminium Nitride piezoelectric film Last but not least, simulation results provide a better way to identify an optimal CMOS structure for the SAW device with high performance in practical Bui Thu Hang Page 53 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Chapter onclusions and Future Work 5.1 Conclusions In the first part of dissertation, the wave propagation characteristics in SAW devices operating in the liquid medium are investigated using the Campbell-Jones method Fundamental understanding of the leaky acoustic wave generation and propagation in SAW sensors with complicated fluid motion is achieved Also, this research considers the operation and suggested structures of SAW device fabricated on other crystal and multi-layered piezoelectric substrates The next part utilizes 3D finite element models to investigate and compare wave propagation characteristics in a typical SAW channel as well as in a novel SAW channel It is concluded that Rayleigh waves are influenced much by the liquid density and liquid motion state whereas the viscosity can be neglected Both LiNbO3 and AlN material are completely suitable for detecting liquid The 3D finite element analysis was performed to investigate the performance of R-SAW sensor for liquid The response of SAW devices under alternating-current excitation showed the benefit of positioning the liquid well in the middle of the two-port SAW delay-line device for enhancing liquid sensing capacity The findings of this research are not only benefit for microfluidic sensors, but also provide a good platform for the study of sensors with the vertical sensing area on other piezoelectric materials This finite element modelling and simulation provides strong meanings for manufacturing and designing R-SAW sensor in practice 5.2 Future work According to the findings of the current research, the following possibilities are discussed as following: Bui Thu Hang Page 54 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation 3D integration system model: It is combination of microfluidic sensor and inkjet or bio-applications The developed 3D model would give insights to evaluate the functioning of integrated microfluidic system as well as optimize the design parameters to obtain the highest performance In the simulation, more efficient ways, such as increasing the mesh density and the investigation time, restraining noise from transverse waves as well as decreasing the error tolerance levels, may provide more accurate analysis of its performance Fabrication process for microfluidic sensor: Which technique is utilized to create exactly the well and large thin film thickness? Development of application – specific integrated circuits: It is necessary to present parametric tests, procedures and experimental setup to check the device fabrication and the layer properties because they can make a fast process control of the deposited/etched layers Moreover, experiment results are used to verify theoretical calculation and simulation results Bui Thu Hang Page 55 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation eference [1] Leslie Y Y and James R F., “Ultrafast microfluidics using surface acoustic waves”, Biomicrofluidics, 2009, 3(1): 012002 [2] Subhas C M., Gourab S G., Yueh-Min R H., “Recent Advances in Sensing Technology”, Springer 2009, ISBN 978-3-642-00577-0 [3] Aisha Q., James R F and Leslie Y Y., “Investigation of SAW Atomization”, 2009 IEEE International Ultrasonics Symposium Proceedings, pp 787-790 [4] Rohan V R., James R F and Leslie Y Yeo, “Particle concentration via acoustically driven microcentrifugation: microPIV flow visualization and numerical modelling studies”, Microfluid Nanofluid (2010) 8:73–84 [5] Aisha Q., Leslie Y Y and James R F., “Interfacial destabilization and atomization driven by surface acoustic waves”, Physics of Fluids 20, 074103 [6] D Morgan, “Surface Acoustic Wave Filters”, Elsevier, New York (1985) [7] D S Ballantine, R M White, S J Martin, A J Ricco and E T Zellers, G C Frye and H Wohltjen, “Acoustic wave sensors – Theory, Design and Physico – Chemical Applications”, Academic Press, 1997 [8] Cleland A.N., “Foundations of Nanomechanics From Solid-State Theory to Device Applications”, Springer 2002, ISBN 3540436618 [9] Ferrari V and Lucklum R , “Piezoelectric Transducers and Applications”, Ed A Arnau Vives, ISBN: 978-3-540-77507-2, 2008, Chapter [10] Tung B D., Thu-Hang B., Dat N T and Trinh C D., “R-SAW Analysis on Single-Crystal AlN Substrate for Liquid Sensors”, ICEMA 2012, pp 13-18 [11] Ying C., “Piezoelectricity in zinc oxide-based multilayer structures for sensor applications”, New Brunswisk, New Jersey, Doctoral thesis 2008 [12] Thu-Hang B., Tung B D., Dat N T and Trinh C D., “Attenuation Coefficient for Surface Acoustic Waves in Fluid Region”, VJM2012, Vol 34, No 4, pp 225-236 [13] Gavignet E., Ballandras S and Bigler E., “Theoretical analysis of surface transverse waves propagating on a piezoelectric substrate under shallow groove Bui Thu Hang Page 56 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation or thin metal strip gratings”, Journal of Applied Physics, Vol 7, pp 6228 - 6233 [14] Thu-Hang B., Dat N T., Tung B D and Trinh C D., “3-D Finite Element Modeling of SAW sensing system for liquids”, The 2012 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, pp 782-787 [15] Shiokawa S and Kondoh J., “Surface acoustic wave sensor for liquid-phase application”, 1999 IEEE ULTRASONICS SYMPOSIUM, pp 445-452 [16] Thomas H H., Chapter Surface Waves [17] Campell J J and Jones W R., “A method for estimating optimal crystal cuts and propagation directions for excitation of piezoelectric substrate waves”, IEEE Trans on Sonics and Ultrasonics, vol SU-15, No 4, 1968 [18] Wilson W C and Atkinson G M., “Rapid SAW sensor development tools” [19] W Richard Smith, H M Gerard, J H Collins and T M Reeder, “Analysis of Interdigital surface acoustic wave transducers by use of an equivalent circuit model”, IEEE Tran on Microwave theory and Techniques, vol MIT-17, No 11, 1969 [20] H Trang, “Design and realization of SAW pressure sensor using Aluminum Nitride”, thesis 2009, Uni Joseph Fourier-Grenoble I Sciences Technologie Sante [21] A Takayanagi, K Yamanouchi and K Shibayama, “Piezoelectric leaky surface wave in LiNbO3”, Appl Phys Lett., Vol 17, No 5, 225-227(1970) [22] K Yamanouchi and M Takeuchi, “Application for piezoelectric leaky surface waves”, Ultrasonics Symposium, pp 11-18(1990) [23] S Tonami, A Nishikata and Y Shimizu, “Characteristics of leaky surface acoustic waves propagating on LiNbO3 and LiTaO3 substrates”, Jpn J Appl Phys., Part 1, Vol 34, No 5B, 2664-2667(1995) [24] J Semmlow, “Signals and systems for bioengineers”, Elsevier Inc ISBN: 978-0-12-384982-3, http://www.elsevierdirect.com, 2nd Edition, 2011 Bui Thu Hang Page 57 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation [25] K Shin and J K Hammond, “Fundamentals of signal processing for sound and vibration engineers”, John Wiley & Sons Ltd, ISBN-13 978-0470-51188-6, 2008 [26] G Zhang, “Orientation of Piezoelectric Crystals and Acoustic Wave Propagation”, 2012 COMSOL Conference [27] J G Gualtiei, J A Kosinski and A Ballato, “Piezoelectric materials for acoustic wave applications”, IEEE Tran on Ultrasonics, Ferroelectrics and Frequency control, vol 41, No 1, 1994 [28] G Bu, D Ciplys and M S Shur, L J Schowalter and S B Schujman, “Leaky Surface Acoustic Waves in single-Crystal AlN Substrate”, International J of High Speed Electronics and Sys., Vol 14, No 3, pp 837-846, 2004 Bui Thu Hang Page 58 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation ppendix: Material Parameters for Piezoelectric Substrate A Lithium Niobate Material constants for Lithium Niobate piezoelectric class 3m symmetry in simulation[27]: ( ( ) ( ) ) ( ) where C11 = 20.3×1010 Nm-2, C33 = 24.5 ×1010 Nm-2, C44 = 6.0×1010 Nm-2, C12 = 5.3×1010 Nm-2, C13 = 7.5×1010 Nm-2, C14 = 0.9×1010 Nm-2, e15 = 3.7 Cm-2, e22 = 2.5 Cm-2, e31 = 0.2 Cm-2, e33 = 1.3 Cm-2, ε11 = 44, ε33 = 29 B Aluminium Nitride Material constants for a non-conducting, non-viscous liquid and Aluminum Nitride piezoelectric in class mm symmetry in simulation [28]: ( Bui Thu Hang ) Page 59 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation ( ( ( ) ) ) ( ) where c11 = 345 GPa, c33 = 395 GPa, c44 = 118 GPa, c12 = 125 GPa, c13 = 120 GPa, = 2.25 GPa, e15 = -0.48 Cm-2, e31 = -0.58 Cm-2, e33 = 1.55 Cm-2, ϵ11 = 9, ϵ33 = 11 ρf = 1000 Kgm-3 and = cl = 1480 ms-1 for the standing liquid Bui Thu Hang Page 60 ... Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Figure 3.5: Top and cross-view of multi-output microfluidic sensor 3.3 FEM Simulation for AlN -based Microfluidic Sensor. .. the vertical SAW sensor Bui Thu Hang Page Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation Moreover, the acoustic wave propagation strongly depends on. .. parameters The design and simulation Bui Thu Hang Page 24 Microfluidic Sensor based on AlN Vertical SAW structure: Investigation, Design and Simulation parameters for FEM simulation are presented