Matti Mantysalo

Body-Worn Antennas Making a Splash: Lifejacket-Integrated Antennas for Global Search and Rescue Satellite System

The Cospas (Cosmicheskaya Sistyema Poiska Avariynich Sudov)-Sarsat Search-and-Rescue (SAR) satellite system provides distress alert and location data to assist rescue operations at sea, in the air, or on land. This paper summarizes the design, development, and verification for a body-worn antenna system interfaced with commercial Cospas-Sarsat personal locator beacons (PLBs), where the implemented system is integrated within an inflatable live vest. The modular approach adopted in the work allows different antenna configurations for different platforms. The electrical and mechanical requirements for antenna materials and antennas were derived from the Cospas-Sarsat system requirements, possible antenna platforms, and the maritime operational environments. The antennas were used in field tests organized in cooperation with the local Cospas-Sarsat search-and-rescue authorities. The field tests were a success. In both cases, low-earth orbit search-and-rescue (LEOSAR) satellites detected the distress signal within minutes, and accurately resolved the location. An additional detection by Geostationary Orbit Search and Rescue (GEOSAR) satellite confirmed the successful operation of the body-worn antenna system.

Screen-Printing Fabrication and Characterization of Stretchable Electronics.

This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2u2009mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag.

Inkjet printing in manufacturing of stretchable interconnects

Stretchable circuits have the potential to enable integrating electronics in everyday objects, but also skin-like, imperceptible electronic applications. However, manufacturing stretchable electronics requires developing novel manufacturing methods and using novel materials at least as substrate. Since the elastic materials for stretchable electronics are relatively soft, using traditional manufacturing methods becomes more problematic, whereas contactless material deposition by inkjet-printing is unaffected by such material properties. This study concentrates on feasibility analysis of using inkjet printing in manufacturing of stretchable electronics. First, printing related challenges are evaluated by manufacturing test structures with inkjet-printer using silver nanoparticle ink on elastic thermoplastic polyurethane substrate and sintering structures in convection oven. Adhesion between ink and substrate, but also sheet resistance, is evaluated. A minimum sheet resistance approx. of 26 mΩ/□ was obtained, and peak strains of inkjet-printed conductors are found to be between 1.0 % and 1.5 %, but conductivity is observed to be almost fully reversible when strain is released.

Laser sintering of copper nanoparticles on top of silicon substrates.

This study examines the sintering of inkjet printed nanoparticle copper ink in a room environment using a laser as a high speed sintering method. Printed patterns were sintered with increasing laser scanning speed up to 400 mm s(-1). The resistivities of the sintered structures were measured and plotted against the scanning speeds. Increased resistivity seems to correlate with increased scanning speed. A selections of analytical methods was used to study the differences in microstructure and composition of the sintered structures. Based on the results, no discernable difference in the microstructure was noticed between the structures sintered using 20 mm s(-1) to 400 mm s(-1) scanning speeds; only the structure scanned using 5 mm s(-1) speed showed a vastly different microstructure and no resistivity was measurable on this structure. Compositional studies revealed that, apart from the structure scanned with 5 mm s(-1) speed which contained the highest oxygen, the rest of the structures showed a steady oxygen increase with increased scanning speed.

Inkjet printed wireless biosensors on stretchable substrate

Wireless biosensors are suited for long-term monitoring of physiological signals. Inkjet printing wireless biosensors on stretchable substrate can be used to realize small and lightweight body monitoring devices. Current conductive inks have low processing temperature which makes it possible to use substrate materials with low temperature resistance. Conductive inks offer sufficient performance for realizing antennas and interconnections between components. In this work, we use thermoplastic polyurethane as the printing substrate. The inkjet printed conductors on polyurethane tolerate only moderate stretching. Despite the weak stretchability, polyurethane is a favorable option in realizing wireless biosensors since even modest stretching enables the biosensor to conform to the human body. The dielectric properties of the polyurethane were characterized using coplanar waveguides (CPW). The determined permittivity of the substrate is 3.2 and the loss tangent is 0.1. Due to high loss tangent CPW lines on polyurethane are much lossier at high frequencies than lines at PEN substrate. The performance of the sensor on PEN is studied with measurements and the antenna performance on polyurethane is investigated using simulations. The measured reading range of the sensor realized on PEN substrate at 300 μm distance from the body was 14 m. According to simulations changing to the lossy polyurethane substrate would not affect the performance of the sensors antenna.

Combination of E-Jet and Inkjet Printing for Additive Fabrication of Multilayer High-Density RDL of Silicon Interposer

The additive nature and high resolution of electrohydrodynamic inkjet (E-jet) printing can be utilized for manufacturing micrometer scale conductive tracks such as those required in the high-density redistribution layers (RDLs) of silicon interposers used in electronics packaging for 3-D integration. Compared to the current lithographic fabrication method, this approach promises to increase the customizability of the process and reduce the amount of waste materials, thereby lowering the costs and the environmental impact of the manufacturing process. In this paper, multilayer interdigitated capacitor and meander resistor structures with 5/5 <inline-formula> <tex-math notation=LaTeX>

Fabrication and electrical characterization of partially metallized vias fabricated by inkjet

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Screen-Printed Curvature Sensors for Soft Robots

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High Resolution E-Jet Printed Temperature Sensor on Artificial Skin

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Evaluation of screen printed silver trace performance and long-term reliability against environmental stress on a low surface energy substrate

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