Leena Ukkonen

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Passive UHF RFID tag consists of a microchip attached directly to an antenna. Proper impedance match between the antenna and the chip is crucial in RFID tag design. It directly influences RFID system performance characteristics such as the range of a tag. It is known that an RFID microchip is a nonlinear load whose complex impedance in each state varies(More)
This paper presents a novel inkjet-printed humidity sensor tag for passive radio-frequency identification (RFID) systems operating at ultrahigh frequencies (UHFs). During recent years, various humidity sensors have been developed by researchers around the world for HF and UHF RFID systems. However, to our best knowledge, the humidity sensor presented in(More)
Wearable RFID tags and wireless sensors can be used for on-body and human monitoring applications. Embroidery with conductive thread provides compelling means for the fabrication of seamlessly garment-integrable antennas for wearable tags and wireless sensors. In this paper, we present the fabrication of fully assembled tags based on embroidered dipole-type(More)
This paper presents a novel temperature sensor tag for passive UHF RFID systems and discusses a method to perform measurements in practice. The developed sensor tag is fabricated from cost-efficient and commercially available materials. Distilled water is used as the temperature sensitive material instead of the more traditional semi-conducting materials.(More)
In Wearable Well-Being project PUHVI, HipGuard system for patients recovering from hip surgery was developed. Novel wireless sensors having 3-axis acceleration and 3-axis magnetic sensors are used to measure patient’s hip and leg position and rotation. Furthermore, capacitive insole sensors are used to measure the force between foot and a shoe. This paper(More)
─ In this paper we provide the basis of using radio frequency identification (RFID) tags for advertisement. Two RFID tags that apply to the 866 MHz and 915 MHz operating frequencies, respectively, were designed based on the logos of two universities participating in this project. Several fabrication methods were used to build the RFID tags on different(More)
This paper presents a fully inkjet printed wireless chipless sensor for carbon dioxide detection. It is composed of two split ring resonators 90 degrees rotated to each other for a total size of 18x46 mm2. The first resonator is used for gas detection whereas the second provides identification of sensor, and a reference for accurate detection. The(More)
We present the simulation-based design of UHF RFID tags based on electro-textile antennas and analyze the impact of recurrent washing on their performance through measurements. The antennas were fabricated from silver plated stretchable fabric made of nylon and elastic fibers. We coated half of the tested samples with acrylic spray to compare the influence(More)
Chye-Hwa Loo, Khaled Elmahgoub, Fan Yang, Atef Elsherbeni* , Darko Kajfez, Ahmed Kishk, Tamer Elsherbeni, Leena Ukkonen, Lauri Sydänheimo, Markku Kivikoski, Sari Merilampi, and Pekka Ruuskanen (1) Department of Electrical Engineering, The University of Mississippi, University, MS, 38677, USA {cloo, kelmahgo, fyang, atef, eedarko, ahmed,(More)
This paper studies a novel RFID-enabled strain sensing approach using the radar cross-section measurement technique and taking advantage of the nonlinearity properties of the RFID chip. As a proof of concept, we applied the method for the measurement of an RFID-enabled strain sensor that was realized on fabric using electro-textiles in order to observe(More)