Ventsislav Yantchev

Chalmers University of Technology, Chemistry and Chemical Engineering, Guest Research Professor

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Ventsislav Yantchev is currently a Guest Professor at the Bio-Physical Laboratory, Dept. Chemistry and Chemical Engineering at Chalmers University of Technology, Sweden. Here I supervise a student on the development of a first in class one port Bio-chemical Resonant SAW sensor integrated with microfluidics and on the development of a new approach based on the "open volume" sensing with micro-acoustic devices.
Until December 2014 Dr. Yantchev was an Associate Professor (Docent) with the Department of Solid State Electronics, The Angstrom Laboratory, Uppsala University, Sweden. Here he originally developed from the fundamentals up the thin film Lamb wave resonator technology for frequency control and sensing applications as well as participated in the development of thin AlN and AlScN film electro-acoustic technology.
Dr. Yantchev received his Ph.D. degree from the University of Sofia, Bulgaria in 2004. The thesis work was focused on the analysis of the Surface Transverse Wave resonators employing a COM model modified by the Plessky's dispersion equations
In 2009 Dr. Yantchev was a recipient of the Goran Gustaffson’s award for younger researchers in Sweden as well as the 4 year Assistant Professor
position by the Swedish Research Council.
Recently Dr. Yantchev serves as a research director as owner of Q-Arts Consulting Ltd., Bulgaria.
His current research interests include the analysis, design, and fabrication of various micro-acoustic wave devices for frequency control, sensing and micro-fluidic applications. Collaboration with industrial partners include development of devices employing the thin film Lamb wave technology, the LSAW technology and TC-SAW technology.

Together with his students Dr. Yantchev received best paper awards at the European Frequency and Time Forum (EFTF) in 2010, 2012, 2016.
In 2012 and 2013. Dr. Yantchev delivered invited talks at the IEEE International Ultrasonic Symposium regarding the development of thin film micro-acoustic Bio-sensors and Lamb wave resonators, respectively. In 2014 Dr. Yantchev has delivered an invited talk to the Joint EFTF - IFCS (IEEE) conference, regarding the development of Surface Phononic Gratings compatible with the planar micro-technology.

Dr. Yantchev is member of the Technical Program Committees of the IEEE IUS and EFTF symposiums.

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Papers by Ventsislav Yantchev

5GHz Band n79 wideband microacoustic filter using thin Lithium Niobate membrane

Electronics Letters

A High-performance Lab-on-a-chip Liquid Sensor Employing Surface Acoustic Wave Resonance: Part II

Journal of Micromechanics and Microengineering

We recently introduced an in-liquid sensing concept based on surface acoustic resonance (SAR) in ... more We recently introduced an in-liquid sensing concept based on surface acoustic resonance (SAR) in a lab-on-a-chip resonant device with one electrical port. The 185 MHz one-port SAR sensor has a sensitivity comparable to other SAW in-liquid sensors, while offering a high quality factor (Q) in water, low impedance, and fairly low susceptibility to viscous damping. In this work, we present significant design and performance enhancements of the original sensor presented in part I. A novel "lateral energy confinement (LEC)" design is introduced, where the spatially varying reflectivity of the SAW reflectors enables strong SAW localization inside the sensing domain at resonance. An improvement in mass-sensitivity greater than 100% at resonance is achieved, while the measurement noise stays below 0.5 ppm. Sensing performance was evaluated through real-time measurements of the binding of 40 nm neutravidin-coated SiO2 nanoparticles to a biotin-labeled lipid bilayer. Two complementary sensing parameters are studied, the shift of resonance frequency and the shift of conductance magnitude at resonance. I.

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Advances in thin piezoelectric film based resonant MEMS technology

2016 XXV International Scientific Conference Electronics (ET), 2016

Complete bandgap SAW phononic resonators

2014 European Frequency and Time Forum (EFTF), 2014

2D composite grating building blocks with hexagonal symmetry are proposed as efficient reflectors... more 2D composite grating building blocks with hexagonal symmetry are proposed as efficient reflectors and transducers in the design of surface acoustic wave (SAW) resonators. Design parameters ensuring complete bandgap characteristics are deduced by means of finite element analysis (FEA). SAW resonators employing phononic building blocks with complete bandgaps are designed, fabricated and tested. Further, the influence of the phononic grating over the spurious responses and the busbar quality are experimentally tested. All test structures are fabricated on 128 Y-X LiNbO 3 using low resolution optical lithography and standard metal deposition and etching routines.

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A Passive Radio Triggered Switch with ID Functionality

Analysis of Q-degradation and Cross-Talk in BAW Sensor Arrays Operating in Conductive Liquid Media

S0 Lamb wave resonators for in-liquid sensing: Promising alternative to shear bulk acoustic wave devices

2016 European Frequency and Time Forum (EFTF), 2016

Electroacoustic Devices utilizing the Lower GHz Frequency band based on High-velocity Laterally propagating Modes in c-oriented AlN thin film membranes - : a Comparative Study

Thin film bulk acoustic resonators (FBARs) for biosensor applications

FBAR filter with asymmetric frequency response and improved selectivity and passband width

Proceedings of the 18th International Conference Mixed Design of Integrated Circuits and Systems Mixdes 2011, 2011

Mass Sensitivity of Thin Film Resonator Device

ABSTRACT A systematic study of the influence of the materials&#39; properties and thickness i... more ABSTRACT A systematic study of the influence of the materials&#39; properties and thickness in composite thin film bulk acoustic resonators (FBAR) on the mass sensitivity is presented. Calculations based on the Mason transmission line model are presented along with some preliminary experimental results. We present and investigate the concept of sensitivity amplification in the mass sensitive regime and show how this amplification correlates with wave reflection and interference within the composite structure. Asymmetrical resonators where the sensitivity differs between the two different surfaces are also presented.

Fabrication of GHz range Oscillators stabilized by nano-carbon-diamond-based surface acoustic resonators

A lot of work has been dedicated to evaluate the interest of Diamond films for the development of... more A lot of work has been dedicated to evaluate the interest of Diamond films for the development of high frequency surface acoustic wave (SAW) devices for various Radio- Frequency (RE) applications. The main interest of such a material consists in its very high acoustic phase velocities. In this work, different research groups are collaborating to identify the capability of diamond-based substrates to allow for the development of SAW resonators at 5 GHz and above, to stabilize RE oscillators in that frequency range. Nano-crystalline diamond (NCD) particularly is investigated in that matter, coupled with various piezoelectric layers. Design of single and double port SAW resonators operating near 5 GHz: are reported, as well as experimental results for SAW resonators built atop the considered material combinations These results allows for identifying the best configuration for the development of high frequency sources.

Lattice FBAR Filters: Basic Properties and Opportunities for Improving the Frequency Response

ABSTRACT The paper contains a relatively detailed consideration of lattice filters with bulk acou... more ABSTRACT The paper contains a relatively detailed consideration of lattice filters with bulk acoustic-wave resonators (FBAR): basic theory, investigation and improving of their design. First FBARs and their parameters are introduced briefly. Then the basic structure of lattice filters and its modification with twice lower number of resonators are introduced. A theory of lattice FBAR filters is presented, which allows unified explanation of many of their properties: condition for small or large gain of the filter; existence of maxima of the filter frequency response; emergence of transmission zeros; etc. The effect of using two different resonators instead of a single resonator in the arms of the lattice filter is investigated next. It is demonstrated that this approach suggests extension of the passband bandwidth and increasing the stopband attenuation. The properties of the considered filters are illustrated by comparing their frequency responses. Similar comparison between some good representatives of lattice and ladder filters is also given at the end, accompanied by comments about the benefits of both filter architectures.

Temperature compensation of liquid FBAR sensors

Journal of Micromechanics and Microengineering, Feb 19, 2007

In this work we demonstrate a practically complete temperature compensation of the second harmoni... more In this work we demonstrate a practically complete temperature compensation of the second harmonic shear mode in a composite Al/AlN/Al/SiO2 thin film bulk acoustic resonator (FBAR) in the temperature range 25 C–95 C. The main advantages of this mode are its higher Q value in liquids as well as its higher frequency and hence higher resolution for sensor applications. For

Dependence of the Electromechanical Coupling on the Degree of Orientation of c-Textured Thin AlN Films

Highly c-oriented thin aluminum nitride (AlN) films have been grown at room temperature with reac... more Highly c-oriented thin aluminum nitride (AlN) films have been grown at room temperature with reactive sputter deposition. Membrane film bulk (FBAR) thickness excited resonators have been subsequently fabricated by bulk micro machining of silicon (Si). The resonators were then electrically characterized with a network analyzer in a one-port configuration. Subsequently, the coupling coefficients and the Q factors of both the longitudinal and the shear mode were extracted from fitting the measured admittance with that of the equivalent circuit model at the resonance frequencies. The goal of this work is to study the variation of the electromechanical coupling and the quality factor of the resonators, for both the longitudinal and the shear modes as a function of the degree of film texture. It is observed that the films exhibit a mean tilt of the c-axis relative the surface normal. This tilt is found to depend on both the film texture and the distance from the wafer radius. It is also demonstrated that the textured films exhibit a behavior of the electromechanical coupling effectively identical to that of a single crystalline material of equivalent tilt. Thus, it is shown that the electromechanical coupling for the longitudinal mode decreases from 8% to 4%, and that for the shear mode increases from 0% up to 3% by varying the full width half maximum (FWHM) of the (002) rocking curve in the interval from 2 to 10 .

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Temperature Compensation of Thin Film Resonators utilizing the Lowest order Symmetric Lamb mode