Ljiljana Zivanov

A Wireless Embedded Resonant Pressure Sensor Fabricated in the Standard LTCC Technology

This paper proposes a fully embedded resonant pressure sensor operating in the MHz range and realized in the standard low-temperature co-fired ceramics (LTCC) technology. Buried sensor design and usage of LTCC materials enable application of this sensor in high-temperature and chemically aggressive environments. Upgraded sensor and sensor-antenna models residing on an analytical concept are used for prediction of the system performance. Also, simulation results show that an increase of Youngs modulus for the LTCC tape diminishes the sensor sensitivity. An experimental setup for wireless data retrieval is designed enabling precise measurement of the influence of pressure variation on the sensors resonant frequency. Experimentally attained results are compared with electrical characteristics determined by analytical calculations as well as those derived from electrical simulations.

Low-Cost CPW Meander Inductors Utilizing Ink-Jet Printing on Flexible Substrate for High-Frequency Applications

This paper describes the design and fabrication of low-cost coplanar waveguide (CPW) miniature meander inductors. Inductors are fabricated on a flexible plastic polyimide foil in ink-jet printed technology with silver nanoparticle ink in a single layer. For the first time, the detailed characterization and simulation of CPW inductors in this technology is reported. The inductors are developed with impressive measured self-resonance frequency up to 18.6 GHz. The 2.107-nH inductor measures only 1 mm × 1.7 mm × 0.075 mm and demonstrates a high level of miniaturization in ink-jet printing technology. The measured response characteristics are in excellent agreement with the predicted simulation response.

Analysis, design, and characterization of ferrite EMI suppressors

In this paper design, modeling and characterization of single and double coils, which consist of conductive layer embedded in the soft ferrite material, are described. These surface-mount components, comprising of a cofired multilayered ferrite and coil, have been developed in the ceramic coprocessing technology. A simple analytical model of proposed structures is presented. This model is very suitable for circuit simulations and for prediction of frequency characteristics of considered inductors. The inductance and impedance of coils embedded in low permeability or high permeability ferrite material are calculated and compared. Also, these suppressors were experimentally tested in the frequency range 1 MHz-3 GHz using an Agilent 4287 A RF LCR meter. The calculated results were in good agreement with the measured ones.

A Novel Approach to Extending the Linearity Range of Displacement Inductive Sensor

This paper presents a meander-type displacement inductive sensor, usable for the detection of small displacements (less than 0.5 mm) in the plane. It also describes design, realization, and the input inductance measurement of sensor. A displacement in two directions can be detected by using two sensor elements, each having a pair of meander coils. In each pair, one of the coils is fixed and between its terminals the input inductance was measured, while the other coil is short-circuited. If one coil is moved above the other, in directions of x - and z -axes, coupling between the coils will change, as well as the input inductance, which serves as a measure of displacement. In order to achieve better linearity of the sensor, longitudinal gaps are inserted in the middle of each conductive segment of one fixed coil. Four sets of inductive sensors were realized: without gap and with three different gaps. Planar, low-cost PCB technology was chosen for our prototype. In addition, an improved model of the inductive sensor is proposed. The input inductance of displacement sensor was calculated and compared with measured values. A good agreement was found.

Modeling and Characterization of Frequency and Temperature Variation of Complex Permeability of Ferrite LTCC Material

This paper presents modeling of the complex permeability spectra, fabrication and a wide frequency range characterization of a toroidal LTCC ferrite sample. A commercial ferrite tape ESL 40012 is used, and standard LTCC (Low Temperature Co-flred Ceramic) processing has been applied to the sample fabrication. The characterization was performed using a short coaxial sample holder and a vector network analyzer in the frequency range from 300kHz to 1GHz, at difierent temperatures. Using the model of the complex permeability spectra dispersion parameters of ferrite LTCC material has been determined for various temperatures. Characteristics of test samples are compared with modeled results and commercially available toroid made of similar NiZn ferrite material.

Characterization of novel varistor+inductor integrated passive devices

This letter describes the design, modeling, simulation, and fabrication of novel integrated passive devices (IPDs). These IPDs, comprising of a cofired multilayered varistor and inductor, have been developed in the ceramic coprocessing technology. The equivalent model of the new structures is presented, suitable for design and circuit simulations. The fabrication method, new design of structures and patented materials of these devices lead to improved characteristics suitable for application in high-frequency suppressors. The IPDs were tested in the frequency range of 1 MHz-3 GHz using an Agilent 4287A RF LCR meter. The measurements confirm the validity of the proposed model.

Passive Wireless Sensor for Force Measurements

The goal of this paper is to investigate fabrication and design of a wireless passive sensor, and its application for measuring normal forces. The proposed force sensor consists of a single coil as an essential part, realized in printed circuit board technology, commercially available elastomer, and ferrite core. Measurements are done wirelessly for variable values of applied force by phase-dip technique, using an external coil antenna. By applying force to the sensor, the elastomer deforms and ferrite approaches to the coil, causing changes to the inductance of the coil. As a result, the resonant frequency of the antenna-sensor system shifts toward lower frequencies. The experimental setup is conducted to test and characterize the developed force sensor. A high sensitivity of 311 kHz/N is achieved in the measured force range from 0 to 75 N. The measurement results proved the theoretical and analytical calculations, as well as the electrical simulations.

A novel application of planar‐type meander sensors

Purpose – The purpose of this paper is to test the measurement performances of a planar‐type meander sensor installed in robot foot in order to examine its potential application as ground reaction force sensor.Design/methodology/approach – A planar‐type meander sensor is composed of two pairs of meander coils. Variation of input inductance between coils serves as a measure of small displacements in a plane. Pairs of meander coils are installed in an actuated robot foot to measure displacements proportional to normal or tangential components of ground reaction force which acts upon the foot. The sensor was modeled by the concept of partial inductance and a new simulation tool was developed based on this concept.Findings – Pairs of meander coils were tested against angular displacements, and results showed that the sensor gives correct information about displacement regardless how the foot touches the ground with its whole area. Deviations between position of computed and real acting point of ground reactio...

Common Mode Chokes for EMI Suppression in Telecommunication Systems

In this paper design of common mode choke (CMC) for EMI suppression in telecommunication systems will be presented. Choke consists of two highly conductive layers embedded in Nickel zinc ferrite. Influences of different ferrite materials and geometrical parameters are analyzed. Software tool ILCMC for calculation of insertion loss of common mode choke has been developed. Using ILCMC simulations have been conducted for different geometrical dimensions of structure and different ferrite materials. Insertion losses of proposed components are calculated and compared.

Transport Parameters of Inkjet Printed Nanoparticle Silver on Polyimide Substrate Measured at Room and Liquid Nitrogen Temperatures

This brief presents the transport parameters of silver layers on a polyimide substrate fabricated by an inkjet printing technology using nanoparticle inks with 20 wt% and 40 wt% silver. All the electrical characteristics of the samples were measured by Hall effect measurement system at 0.37 T. The electron mobility in inkjet printed silver layer was 7.07 and 4.58 cm²/V s for 20 wt% silver, 29.6 and 21.3 cm²/V s for 40 wt% silver at 77 and 300 K, respectively. The resistivity in inkjet printed silver layer with 20 wt% is 20.6×10^-6 and 27.1×10^-6Ω cm, and 4.81×10^-6 and 8.27×10^-6Ω cm for 40 wt% silver at 77 and 300 K, respectively. The surface morphology and profiles of the samples were obtained with an atomic force and scanning electron microscope.