Jari Hannu

Enabling Remote Testing: Embedded Test Controller and Mixed-signal Test Architecture

Remote testing requires embedded test infrastructure, consisting of communication, test control and test access. This article presents an embedded test solution for a low-frequency audio board. Supporting analog testing, the solution consists of a measurement and calculation method for passive component characterization, analog test bus solution and an embedded test controller for controlling embedded tests and providing test stimuli. Moreover, the solution, which supports the presented test plan, was compared to a test plan supporting traditional testing. It was found that the embedded test solution provided a 29% test coverage of the audio board components and substituted flying probe testing included in the traditional test plan. Besides such benefits as improved fault diagnostics and lower manufacturing costs, the paper also discusses the drawbacks of the presented solution, including reduced measurement accuracy. This paper also presents a correction to a previously presented passive component measurement and calculation method.

Piezoelectric circular diaphragm with mechanically induced pre-stress for energy harvesting

This paper presents the results of a piezoelectric circular diaphragm harvester utilising a unique measurement setup with tailored input force (walk profile), adjustable mechanical pre-stress, and simultaneous measurement of the harvested energy output and input force pressure. The harvester, incorporating the pre-stressing mechanism, consisted of a 191 ?m thick PZ-5A piezoelectric disc (? 34.5 mm) and a 100 ?m thick steel plate (? 45.5 mm). Its performance was measured with pressure cycles at a frequency of 0.96 Hz. Harvested energy was measured as a function of the pre-stressing state, the applied force, and the pressure profile. The optimal bending pre-stress was found to improve the efficiency of harvesting by ?141% compared to the case without pre-stress. The maximum obtained efficiency was 14.7%, and the maximum average power density of 6.06 mW cm?3 was measured for a unimorph diaphragm energy harvester. The results show that the pre-stressing technique is an effective method to improve the efficiency and generated power in this type of piezoelectric harvester, potentially enabling it to power different portable devices and sensors in future applications.

Hybrid Foam Pressure Sensor Utilizing Piezoresistive and Capacitive Sensing Mechanisms

The development of flexible and stretchable sensing for future applications, e.g., strain, force, and pressure, requires novel foam and foam-like structures with properties such as fast relaxation times, a wide linear response range, good sensitivity to different stimuli and repeatability, without compromising low-cost, simple and effective manufacturing methods, and excellent mechanical properties. We present a new type of hybrid foam pressure sensor that utilizes a combination of piezoresistive and capacitive sensor elements. The hybrid foam sensor shows a maximum pressure sensitivity of 0.338 kPa−1 and a linear response of 0.049 kPa−1 in the piezoresistive and capacitive sensor elements, respectively, in the pressure ranges of <5 and 0–240 kPa, respectively. The response and recovery times of both sensor elements were similar, ≤200 ms, at various pressures. In addition, the properties of the hybrid foam sensors, e.g., sensitivity and response and recovery times, can be tuned in various ways, such as by changing the thickness of the composition of the foam. In addition, the materials are easily accessible and the sensor can be cost-effectively manufactured and changed for different purposes. The relatively high sensitivity of the piezoresistive sensor element enables object manipulation from low pressure (≥21 Pa) to high pressure (>80 kPa). Simultaneously, both the sensor elements can be used for impact measurements across a wide range of pressures up to ≥240 kPa. Thus, the concept of the hybrid foam sensor could be utilized widely for sensing of pressures, impacts, or even bending in various applications, e.g., wearable electronics.

Enhancing polarization by electrode-controlled strain relaxation in PbTiO3 heterostructures

A large remanent polarization close to theoretical value 80 μC/cm2 of bulk PbTiO3 is achieved in epitaxial heterostructures of (120–600)-nm-thick PbTiO3 films grown by pulsed laser deposition on (001) SrTiO3 substrate using a 100-nm-thick SrRuO3 bottom electrode layer. The heterostructures employing a 50-nm-thick electrode exhibit a significantly smaller polarization of ≤60 μC/cm2. A detailed x-ray diffraction analysis of the crystal structure allows for relating this large polarization to electrode-controlled relaxation of epitaxial strain in PbTiO3. Based on the observed results, we anticipate that the electrode-promoted strain relaxation can be used to enhance polarization in other epitaxial ferroelectric films.

Dielectric properties of novel polyurethane–PZT–graphite foam composites

Flexible foam composite materials offer multiple benefits to future electronic applications as the rapid development of the electronics industry requires smaller, more efficient, and lighter materials to further develop foldable and wearable applications. The aims of this work were to examine the electrical properties of three- and four-phase novel foam composites in different conditions, find the optimal mixture for four-phase foam composites, and study the combined effects of lead zirconate titanate (PZT) and graphite fillers. The flexible and highly compressible foams were prepared in a room-temperature mixing process using polyurethane, PZT, and graphite components as well as their combinations, in which air acted as one phase. In three-phase foams the amount of PZT varied between 20 and 80 wt% and the amount of graphite, between 1 and 15 wt%. The four-phase foams were formed by adding 40 wt% of PZT while the amount of graphite ranged between 1 and 15 wt%. The presented results and materials could be utilized to develop new flexible and soft sensor applications by means of material technology.

Failure mode characterization in inkjet-printed cpw lines utilizing a high-frequency network analyzer and post-processed tdr analysis

Failure mode characterization was applied to coplanar transmission lines by utilizing 0.5{10-GHz S-parameter measurements and post-calculated TDR (Time-Domain-Re∞ectometry) analysis. Coplanar waveguide transmission lines were inkjet-printed on 1.0-mm- thick ∞exible plastic RF substrates. Inductive, resistive, and capacitive types of failures | as the main failure modes caused by manufacturing, bending, or thermal cycling stresses | were investigated. The inkjet- printed CPW (Co-Planar Waveguide) lines were damaged by inductive shorts due to mechanical hitsor resistive and capacitive failures due to bending of the substrate. By using the TDR method the type and physical location of the failure can be determined.

Current State of the Mixed-Signal Test Bus 1149.4

This paper presents the current state of the IEEE standard for a Mixed-Signal Test Bus 1149.4 and examines proposed modifications and alternatives. The standard was published in 2001 and got its first major update in 2011 which included description language support. Although the standard has not gained high usage in the electronics manufacturing industry, research has been undertaken to improve its usability. The main research topic has been the test methods for discrete components and analog circuits but the usage of the analog test environment for various applications has also been considered. The proposed modifications for 1149.4 aim to exceed the current limitations of the standard such as the inability to perform RF testing or to access problems in multichip packages. The alternatives for the standard are examined, focusing on other testability standards and also emerging standards such as IJTAG. The alternative test methods and standards cannot directly replace the 1149.4, especially on board level mixed-signal testing.

Methods of Testing Discrete Semiconductors in the 1149.4 Environment

This paper describes measurement methods for testing discrete semiconductors in the environment defined by the IEEE 1149.4 standard for a mixed-signal bus. First, the paper introduces and illustrates measurement procedures for obtaining such essential electrical parameters of diodes and transistors as can be used for testing and identification. Then, the procedures are carried out and the achieved measurement results presented. To demonstrate the usability of the measurement procedures, the paper then presents test methods and measurement results for discrete component blocks. The results indicate that testing and measuring some of the electrical parameters of discrete semiconductors is possible in the 1149.4 environment. These parameters allow the determination of whether the component under test is working properly or not. Our tests only covered the semiconductors’ DC features, disregarding their AC features. Also discussed are limitations of the 1149.4 environment in discrete semiconductor testing.

Embedded health monitoring strategies for aircraft wiring systems

Health and usage monitoring of structures and active systems has received a wealth of attention in recent years. Microsystems are seen as a core technology for the realisation of these monitors as they offer the potential for multi-sensor integration with active electronics, wireless connectivity and in the future a self-powering capability. This article focuses on solutions for aircraft wiring systems where on-line detection of degradation and incipient failure would deliver improved safety and enhanced maintenance efficiency. Several approaches are presented to the problem of wire degradation detection in terms of both test and monitoring strategies. Both electric and mechanical (acoustic) methods will be presented together with simulation and experimental results.

Capability Assessment of Inkjet Printing for Reliable RFID Applications

In this paper, inkjet-printed silver traces and interconnections produced with the print-on-slope technique were used in an radio-frequency identification (RFID) structure operating in the ultra-high-frequency range. Underfill material was used to attach silicon RFID chips onto flexible, 125-