Toni Björninen

Toni Björninen
Tampere University | UTA · Faculty of Information Technology and Communication Sciences

Doctor of Science in Technology

About

191
Publications
49,957
Reads
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3,543
Citations
Citations since 2017
76 Research Items
2411 Citations
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20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Introduction
I am an Academy of Finland Research Fellow in Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland. I have been a Postdoctoral Scolar in Berkeley Wireless Research Center in UC Berkeley and in Microwave and Antenna Institute in Tsinghua University, Beijing. My research focuses on technology for wireless health including implantable and wearable antennas and sensors and RFID-inspired wireless systems. My teaching experience covers undergradute and graduate level courses on passive and active RF/microwave circuits, antennas and RFID.
Additional affiliations
January 2017 - August 2021
Tampere University of Technology
Position
  • Academy of Finland Research Fellow
Description
  • Academy of Finland funding decision 294616.
September 2016 - December 2016
Tampere University
Position
  • Academy of Finland Research Fellow
Description
  • Academy of Finland funding decision 294616.
September 2013 - August 2016
Tampere University
Position
  • Academy of Finland Postdoctoral Researcher
Description
  • Academy of Finland funding decision 265768.
Education
January 2010 - June 2012
Tampere University
Field of study
  • Electrical Engineering

Publications

Publications (191)
Article
Full-text available
Rapid advances in antennas, propagation, electromagnetics, and materials are opening new and unexplored opportunities in body area sensing and stimulation. Next-generation wearables and implants are seamlessly providing round-the-clock monitoring. In turn, numerous applications are brought forward with the potential to ultimately transform healthca...
Article
Full-text available
This article presents a method of obtaining an equivalent lumped element circuit to model the electrical connector-line transitions in the ultra-high frequency (UHF) band. First, the scattering matrices of two microstrip transmission lines that are otherwise identical but have the physical lengths of d and 2d are measured. Next, the theoretical mod...
Article
Full-text available
We present a meandered triple-band planar-inverted-F antenna (PIFA) for integration into brain-implantable biotelemetric systems. The target applications are wireless data communication, far-field wireless power transfer, and switching control between sleep/wake-up mode at the Medical Device Radiocommunication Service (MedRadio) band (401–406 MHz)...
Article
Full-text available
We present a quasi-Yagi antenna mounted on a periodic surface for a wearable UHF RFID reader operating in the UHF RFID frequency band centered at 915 MHz. The periodic surface was co-optimized with the antenna to enhance the launching of surface waves to enable the end-fire radiation along the forearm so that a user can identify objects by pointing...
Article
Full-text available
We present a wearable passive UHF RFID tag based on a circularly polarized (CP) patch antenna on a textile substrate. The antenna miniaturization is based on applying a combination of the cross- and L-shaped slots in the radiator. In conjunction, the right-hand circular polarization is achieved by asymmetrically truncating all four corners of the s...
Chapter
The major challenge in developing a wireless brain implant is to establish a stable and efficient trans‐cranial wireless link with an integrated implantable antenna. This chapter discusses the challenges in developing the intracranial implantable antennas and compares different techniques for wireless power transfer in the presence of human body ti...
Article
Optically transparent flexible tag antennas are highly desired for some applications, where unobtrusiveness and capability of mounting on curved surfaces are required. On the other hand, circular polarization minimizes signal degradation due to polarization mismatch between the reader and tag antennas, thus ensuring good communication quality and a...
Article
Full-text available
In this paper, two pairs of compact microstrip antennas were introduced for a dual-unit retinal prosthesis operating at two frequencies of 1.45 GHz and 2.45 GHz. For 2.45 GHz frequency band, a triangular microstrip antenna with shorting pin and 7 × 6.93 × 0.63 mm dimensions is explored to enhance intraocular element bandwidth. Also, a modified rect...
Article
Full-text available
In this article, a modified microstrip Wilkinson power divider with harmonics suppression for GSM communications applications is presented. For low-pass filter designing, one open stub, one radial resonator, and two rectangular resonators are used. According to results related to insertion losses (|S 21 | and |S 31 |), stopband is wide and equal to...
Article
Wireless intracranial implantable microsystems are believed to potentially innovate the management of brain disorders and the treatment of neurological diseases. The fundamental challenge in the development of the wireless implantable system is the attainment of miniature antennas achieving adequately high efficiency for signalling and wireless pow...
Article
Full-text available
We present a quasi-Yagi RFID tag antenna headgear to produce a high read range and a directive beam from the user's head. For our approach to the antenna development, we manipulated the reflector of the quasi-Yagi antenna as another dipole antenna which generates a directive radiation pattern upwards from the user's head, thus simultaneously achiev...
Conference Paper
Full-text available
We present a compact circularly polarized (CP) antenna for wearable passive UHF RFID tags. The antenna is a square-shaped microstrip patch antenna where we have applied corner truncation and slotting techniques in the top layer conductor for achieving the CP property and a shorting pin and loop structure for impedance matching. Despite using a low-...
Conference Paper
We present a headband loop antenna for wireless power transfer to multiple IMDs located in the cranial cavity at the depth of 10 mm from the skin. We characterize the wireless power transfer link in terms of the power gain and the power delivered to the IMD, when maximum SAR compliant transmission power is fed to the headband antenna at frequency o...
Conference Paper
Full-text available
We present a dual-ID RFID headgear based on quasi-Yagi antenna where we reuse the reflector element as second dipole antenna that provides radiation pattern upwards from the user’s head. Thus, we achieve simultaneously the broadside and end-fire patterns without increasing the size of the antenna platform. For avoiding the unpredictable impact of t...
Article
Full-text available
Characterization of unconventional materials is essential in the field of microwave engineering. In this study, we present a method for the microwave characterization of conductive and non-conductive textile materials. Our approach is based on fitting the material parameters of a numerical microstrip transmission line model so that the simulated si...
Article
Full-text available
In this paper, we present experimental investigations on washing durability of polydimethylsiloxane (PDMS)-conductive fabric composite, to validate its applicability for realization of flexible wearable antennas that can withstand multiple washing cycles. For this purpose, we designed an ultra-high frequency (UHF) radio frequency identification (RF...
Conference Paper
Full-text available
We present a wearable slotted patch antenna embedded in a glove for wearable UHF RFID reader. The antenna is fully-textile based, small enough to fit on the area in the back of the hand and achieves the realized gain of −1.3 dBi at 866 MHz in body-worn configuration. The paper outlines the numerical optimization of the antenna using a layered hand...
Conference Paper
Full-text available
Semi-passive RFID sensor possesses longer interrogation distance and advanced functionalities compared with the fully passive ones. Utilizing the wireless energy harvesting, we present a semi-passive RFID sensor platform without the reliance on the external battery. We outline the sensor system development and conduct the wireless measurement of th...
Conference Paper
Full-text available
We present a quasi-Yagi antenna that provides low- profile and endfire radiation for a wearable RFID tag placed on top of the head. The antenna provides directivity of 4.9 dBi in the direction where the user is facing. This is a contrasting feature compared with most wearable antennas radiating towards the direction of the body surface normal....
Article
Full-text available
We present a glove-integrated slotted patch and split ring resonator (SRR) antennas for a wearable UHF RFID reader operating at 866 MHz. The prototype antennas are made of adhesive electro-textile on low-permittivity foam material. To characterize the antennas, we tested them wirelessly in communication with a common dipole type RFID tag to estimat...
Conference Paper
Full-text available
We present an RF energy harvesting system where two distinct passive UHF RFID microchips provide different tag IDs to detect low and high states of the harvester’s charge storage. This enables the backend system to acknowledge when the harvesting system is ready for advanced power consuming operations. Overall, we were able to read the separate IDs...
Conference Paper
Full-text available
Far-field RF energy harvesting is a convincing approach for energizing low-power wireless devices. In this work, we present a passive UHF RFID tag combined with an RF-energy harvester where a low-power switch circuitry changes the tag's ID as the voltage at the harvester's storage capacitor exceeds a certain threshold. This way, an RFID reader can...
Article
Full-text available
In this paper we present a new approach to realize flexible transparent strain sensors. It combines the use of transparent conductive fabric with polydimethylsiloxane (PDMS) through a simple and straightforward layer-by-layer assembly process. The conductive fabric is used to realize the transparent electrodes while the PDMS is utilized as both the...
Conference Paper
Full-text available
We establish a passive UHF RFID tag as a sensor with a referenced readout to compression. We introduce the sensor tag design, which is based on a two-part split ring resonator antenna, and present the compression sensor platform with a reference tag. We analyze the achieved wireless measurement results and evaluate the performance of the compressio...
Article
Full-text available
We present our study on PDMS-embedded conductive fabric, which we propose as a simple yet effective solution to the challenging issue of poor PDMS-metal adhesion, allowing for a relatively easy realization of robust flexible antennas for wearable applications. The method combines the use of conductive fabric as a radiator with polydimethylsiloxane...
Article
Full-text available
Robustness evaluation is a critical part to verify the applicability of wireless implantable devices. In this work, we present a semi-anatomical ellipsoid head model to evaluate the robustness of a split ring resonator inspired antenna system toward variable implant location, tissue layer thicknesses, and antenna orientation with respect to the hum...
Conference Paper
We present a circularly polarized tag antenna using textile materials for wearable passive ultra high frequency (UHF) radio frequency identification (RFID) system. A corner-truncated square patch with a shorting pin and an inductive feed network are used to achieve circularly polarization and conjugate impedance matching. The antenna has similar be...
Conference Paper
Human body phantom with electrical properties are widely used in electromagnetics solvers to model the lossy human tissue environment. The selection of the phantoms affects the computational efficiency and results accuracy. In this work, we evaluated three human head phantoms with an intracranial implantable antenna. Results of phantom complexity a...
Conference Paper
This paper presents a loop antenna for deep implant powering in an intracranial pressure (ICP) monitoring application. This work is continuation of our on-going development of a wirelessly powered implantable system for ICP monitoring. Experimental results indicate that the implant can be activated until the depth of 19 mm from the skin. This is 8...
Conference Paper
Full-text available
This paper presents a radio frequency (RF) energy harvesting unit integrating a passive UHF RFID tag as a RF switch. The presented system has two main parts: energy harvesting unit and RF switch. Energy harvest unit converts the RF-to-DC and charges the capacitor. The RF switch, consists of a Pin diode and UHF RFID tag, monitors the capacitor volta...
Conference Paper
We present a circularly polarized antenna for wearable passive UHF RFID tag. The antenna consists of two layers without physical connection. The upper layer is for achieving circular polarization by two orthogonal meandering dipoles connected to a split ring . The lower layer is a split ring resonator structure to achieve complex conjugate impedanc...
Conference Paper
We present a passive UHF RFID tag based on a spatially distributed split ring resonator antenna system. The physically separated parts of the tag form a remotely detectable platform, which can be partly implantable and partly wearable. This is the first stage in our research toward a RFID-inspired wireless intra-abdominal pressure sensor. The tag c...
Article
Full-text available
Analysis of the structure of the level sets of transducer power gain and voltage gain of a two-port network enables a semi-analytical method for finding the extrema these performance indicators as the port terminations vary in bounded rectangles in the complex plane. In particular, we show that the extrema are necessarily attained in small-dimensio...
Article
Full-text available
We compare the performance of equal-sized dipole and folded dipole wearable passive UHF RFID tags using three different body models for the torso of an adult male: cuboid and anatomical models with and without internal structures. The results show that all models estimate the antenna impedance matching appropriately, but only the anatomical models...
Article
Full-text available
We propose a spatially distributed antenna system to serve as the radio platform for RFID inspired brain care applications. The antenna system consists of a passive wearable part placed on the scalp and a cortical implant part with split ring resonator topology for miniaturization and antenna self-matching with a backscattering microsystem. We have...
Conference Paper
We present two wearable passive UHF RFID tags based on electro-textile folded dipole and slot antennas, which have the same footprint area. We simulated the antennas in a box model and optimized them to operate near the human body. The antennas were manufactured from commercial electro-textile material by a laser cutter and reference antennas were...
Conference Paper
This paper presents the fabrication and wireless evaluation of embroidered passive UHF RFID tags on a 3D printed (NinjaFlex) substrate. The paper outlines the details of the 3D printing of the substrate, the characterization of the substrate material at the UHF band, the embroidery process using conductive yarn, and the wireless measurement results...
Conference Paper
We present a wearable e-textile passive UHF RFID tag based on a split ring resonator antenna. The antenna was optimised using a full-wave electromagnetic solver and the prototyped tag was tested in wireless measurements. The detection range of the tag is 2.8 metres at 915 MHz when affixed to the upper back of a person on a textile substrate with...
Article
This paper presents a 3D loop antenna to overcome the impact of small lateral misalignment of the order of 2 mm between the inductively coupled antennas. This work is a continuation of our previously reported work. In our previous work, we have successfully activated the pressure monitoring sensor and performed the pressure readout for an intracran...
Conference Paper
Full-text available
We summarize the possibilities of embroidery with conductive yarn in the fabrication of antennas and antenna-electronics interconnections for wearable RFID tags. Based on our results, both fabrication time and amount of conductive yarn used in fabrication of a dipole antenna can be saved by selecting dense or parse stitching for different regions o...
Conference Paper
Full-text available
We present a slot antenna with the footprint size of 4 4 cm2 (0.12λ 0.12λ at 915 MHz) for wearable passive UHF RFID tags. In addition to the main radiating slot, cuts made into the surrounding conductor increase the antenna radiation efficiency and help to self-match the antenna impedance with the RFID microchip in the body-worn configuration. Ante...
Article
An implantable pressure monitoring system is a compelling approach to home monitoring of intracranial pressure in the long term. In our approach, an on-body unit powers a cranially concealed system where a piezoresistive element senses the pressure. A data transmission unit built in the same platform emits a signal at a pressure dependent frequency...
Conference Paper
An implantable pressure monitoring system is a compelling approach to home monitoring of intracranial pressure in the long term. In our approach, an on-body unit powers a cranially concealed system where a piezoresistive element senses the pressure. A data transmission unit built in the same platform emits a signal at a pressure dependent frequency...
Conference Paper
Embroidery is an efficient method for the fabrication of textile antennas. We studied the effects of reducing the amount of conductive thread to achieve savings in material costs and the effects of the sewing pattern on the wireless performance of embroidered passive UHF RFID tags on two different fabric substrates. The antennas were sewed on cotto...
Conference Paper
This paper presents the pressure readout results from a piezoresistive pressure sensor in a biological environment mimicking the human head properties for intracranial pressure (ICP) monitoring application. The piezoresistive pressure sensor is wirelessly powered through inductively coupled antennas. After successful activation of the sensor, the p...
Article
Full-text available
We present a wearable passive UHF RFID tag based on a slotted patch antenna comprising only textile materials (e-textile, textile substrate, conductive yearn). As a novel manufacturing approach, we realize the patch-to-ground and antenna-to-IC interfaces using only conductive thread and a sewing machine. We outline the electromagnetic optimization...
Article
Monitoring of intracranial pressure (ICP) provides a life-saving diagnostic tool. We present a battery-free pressure sensing system for minimally invasive ICP monitoring. It comprises a cranially concealed wireless pressure sensor and on- and off-body external units. The sensor is based on a piezoresistive element and is inductively powered through...