Long-term Reliability Research Articles

The exeter cemented stem provides outstanding long-term fixation and bone load at 15years follow-up: A systematic review and meta-analysis.

Since its introduction in 1988, the double-tapered polished Exeter cemented stem has been widely adopted in primary total hip arthroplasty (THA). Despite the results coming from the arthroplasty registries have proven great survivorship, the aim of this study was to dig deeper and describe the modes of failure of the Exeter stem at 15years follow-up while reporting the clinical and radiographic outcomes. A search of PubMed, MEDLINE, and Embase was performed using the Preferred Reporting Items for Systematic Review and Meta-Analyses since inception of database to January 2022. A meta-analysis was performed on stem's failure rates and clinical outcomes using random effects models. Publication bias was assessed with funnel plots. Overall, ten studies met the inclusion criteria with 2167 hips at mean 14.8 ± 4.1years follow-up. The meta-effect estimate for revision rate for stem-related reasons was 3.8% (CI 95% 2.1-5.6, p < 0.01). The meta-effect for revision rate for stem aseptic loosening (AL) was 0.22% (CI 95% 0-0.4, p = 0.048) and for periprosthetic fracture was 0.6% (CI95% 0.3-0.9, p < 0.001). The meta effect estimate for Oxford Hip Score (OHS) at final follow-up was 32.4 (moderate; CI 95% 23.2-41.6, p <0.001) with and heterogeneity among the studies of I2 0%. Radiolucent lines were reported in 5.5% of cases, with 1.0% of cases (21 hips) reported to be progressive. Current evidence suggests that the Exeter cemented stem not only has proven long-term outstanding reliability with a revision rate of 3.8%, but also incredibly low revision rates for AL (0.22%) and periprosthetic fracture (0.6%). It is suitable for a variety of indications, and the consistent radiological appearances indicate durable fixation and load transmission while being associated with a remarkably low stem-related complication rate.

Long-term reliability assessment of ceramic water filters: strength and electro-kinetic parameter studies

Long-term reliability assessment of ceramic water filters: strength and electro-kinetic parameter studies

Carbohydrate-protein interaction-based detection of pathogenic bacteria using a biodegradable self-powered biosensor.

Battery-free and biodegradable sensors can detect biological elements in remote areas. The triboelectric nanogenerator (TENG) can potentially eliminate the need for a battery by simply converting the abundant vibrations from nature or human motion into electricity. A biodegradable sensor system integrated with TENG to detect commonly found disease-causing bacteria (E. coli) in the environment is showcased herein. In this system, D-mannose functionalized 3D printed polylactic acid (PLA) with the brush-painted silver electrode was used to detect E. coli by a simple carbohydrate-protein interaction mechanism. The adsorption capacity of D-mannose is generally altered by varying the concentration of E. coli resulting in changes in resistance. Thus, the presented biosensor can detect bacterial concentrations by monitoring the output current. The PLA TENG generates an output of 70 V, 800 nA, and 22 nC, respectively. In addition, tap water and unpasteurized milk samples are tested for detecting bacteria, and the output is measured at 6 μA and 5 μA, respectively. Further, the biosensor was tested for biodegradability in soil compost by maintaining constant temperature and humidity. This study not only proposes an efficient and fast method for screening E. coli but also gives important insights into the ability to degrade and long-term reliability of TENG-based sensor platforms.

Quality assessment of reliability engineering systems

Quality and quality assessment are key indicators in many fields. There exist various interpretations of the quality concept, such as technical, legal, and economic definitions. The fundamental aspect of technical systems is the quality problem, and there are different ways to assess quality. This paper examines the relationship between quality and reliability that forms the basis of the safety property and offers a quality assessment that relies on system reliability characteristics using a mathematical methods. Reliability is influenced by random concepts and events, such as the moment of failure. Costly long-term reliability tests on a large number of products are required to determine whether a particular object is suitable. As an example, the reliability of the redundant recoverable system is considered. Reliability influences the security property. Failure of an object decreases the values of the remaining properties dramatically. The theory of random processes, including the use of the theory of Markov processes, is a rational mathematical technic for solving reliability problem. Quality assessment tasks can also be attributed to management tasks, which are becoming increasingly popular in various areas. As an example, the reliability of the redundant recoverable system is considered. The paper uses the generally accepted concepts of the probability, reliability function, failure rate, etc.

A Reconfigurable AC Power Cycling Test Setup for Comprehensive Reliability Evaluation of GaN HEMTs

To address the challenges in long-term reliability testing of GaN power devices, this paper proposes a reconfigurable AC power cycling test setup. While addressing the limitations of existing aging tests, the proposed setup enables accelerated aging of GaN devices under a wide range of realistic stress conditions. Specifically, various hard and soft switching modes can be tested to realistically emulate different application scenarios. In addition to the ability to control test temperature, the setup also features adjustable power loop inductance that enables precise control over voltage overshoot during hard switching transients. Further, an on-state resistance based junction temperature estimation technique is used for closed loop junction temperature control. For this, a fast drain-source voltage measurement circuit along with an algorithm for closed-loop control of the mean junction temperature is presented in detail. Furthermore, the magnitudes of the temperature swing under different operation conditions are discussed in depth which provides a good insight to control temperature swings. Finally, a prototype is built to validate the proposed test design.

Advancements and applications of piezoelectric energy harvesters: A comprehensive review

This paper reviews current research on piezoelectric energy harvesting devices for low-frequency applications (0- 100Hz). It explores the challenge of optimizing energy output due to the high elastic moduli of piezoelectric materials. Key aspects contributing to harvester performance are discussed, aiming to minimize reliance on external power and maintenance for devices like wireless sensor networks. Optimizing geometry and dimensions of piezoelectric elements enhances energy conversion efficiency by matching vibration frequencies. Efficient energy management circuits are crucial for capturing and storing harvested energy effectively. These circuits must be capable of efficiently converting the AC output of the piezoelectric harvester into a stable DC voltage suitable for powering electronic devices or charging energy storage devices such as batteries or capacitors. In addition to material and design considerations, environmental factors such as temperature variations and humidity levels can significantly impact the performance of piezoelectric energy harvesters. Therefore, robust encapsulation techniques must be employed to protect the harvester from adverse environmental conditions while ensuring long-term reliability. Overall, this paper provides insights into the current challenges and advancements in the field of piezoelectric energy harvesting for low-frequency applications, offering valuable perspectives for future research and development efforts in this area.

Precision and Performance Evaluation of Accelerated Aging System for DC TP Power Cables

The demand and necessity of direct current (DC) has been increasing owing to large capacity and long distance power transmission. DC application of TP (thermal plastic) materials, which can increase the power transmission capacity compared to existing insulation materials, has been the primary focus of existing studies. This study presents the development of a highly reliable accelerated aging system that can implement the aging conditions of DC power cables. Moreover, we verify its reliability by testing TP model cables and analyzing the aging characteristics. Accordingly, we developed an accelerated aging system that can simulate thermal, electrical, and mechanical stresses collectively. We used the accelerated aging system to perform an accelerated aging test of the TP model cable for 40 cycles. The control precision of the accelerated aging system during the test was numerically calculated. The system was evaluated by using the conduction current and chemical characteristics of the aged TP model cables. The experimental results show that the precision of accelerated aging system is 1 % for 1 cycle. The conduction current of the aged TP model cables was increased by more than 100% before aging, thereby it is verified the performance of the system accelerates the aging of power cables. It is expected that the highly reliable accelerated aging system of power cables can be used to perform long-term reliability tests and as diagnostic technology during the development of DC power cables.

온도 및 조사강도 통합보정을 통한 태양광모듈의 전력측정법에 대한 연구

Power measurement for photovoltaic(PV) modules is a key factor in evaluating the performance, safety, and long-term reliability of photovoltaic modules. The power measurement for the PV module is made by measuring the electrical characteristics by a solar simulator, which is an artificial solar light source. These solar simulators are divided into two types, which are the pulse-type simulator and the continuous type simulator. In the pulse simulator, the temperature characteristics are stabilized and there is not temperature difference between the inside and outside of the solar module to be measured. The continuous irradiation simulator has fluctuations in temperature characteristics due to continuous light irradiation, and there is a temperature difference between the inside and outside of the PV module to be measured. The variability of these temperature characteristics can be improved through temperature correction. In addition, the convenience of measurement can be improved by predicting the power and correcting the irradiance to the temperature correction. The integrated correction of temperature and irradiance proposed in this paper can be contributed to the power measurement of PV modules in the continuous type simulator.

Long-term test-retest reliability of the vestibular/ocular motor screening for concussion in child athletes: A preliminary study

The Vestibular/Ocular Motor Screening (VOMS) is a sport-related concussion screening tool that assesses vestibular ocular reflex (VOR) and oculomotor symptom provocation. Long-term test-retest reliability of the VOMS over multiple athletic seasons has not yet been established in a pediatric population. Fifty-one child athletes (females = 28, 54.9%) 8–13 years of age, completed a baseline VOMS assessment at two timepoints, 18 months apart. Cronbach’s alpha was used to examine the internal consistency at both time points. Two-way mixed intra-class correlation coefficients and Cohen’s Kappa statistics were used to evaluate test-retest reliability. High internal consistency existed at both initial (α = 0.91) and follow-up (α = 0.95) for VOMS symptom provocation items. Strong inter-item correlations were noted between vertical VOR (r = ≥0.70) and visual motion sensitivity (VMS) (r = ≥0.70). Fair agreement was produced for convergence (κ = 0.23, vertical VOR (κ = 0.25) and VMS (κ = 0.25), as well as reliability on NPC distance (ICC2, k = 0.31). All other VOMS scores yielded poor agreement between time points. Symptom provocation was the same for 49% of athletes between timepoints, while 31.4% had a decrease in scoring at follow-up. Symptom provocation from VOMS tasks lessened with increasing age and time; therefore, clinicians should consider annual baseline testing to improve accuracy for concussion evaluation and management in pediatrics.

Fast electromigration stress analysis using Low-Rank Balanced Truncation for general interconnect and power grid structures

Electromigration (EM) has become one of the most significant challenges considering longterm reliability in integrated circuit design. The problem is caused by the large current density in circuit interconnections. However, in most cases, we are interested in the EM stress at specific points of the interconnect, such as vias, junctions and boundaries. As a result, Model Order Reduction (MOR) techniques can provide attractive methodologies to reduce the complexity of the original systems. System-theoretic techniques like Balanced Truncation (BT) offer very reliable bounds for the approximation error, compared to moment-matching methods. In this paper, we apply a computationally efficient Low-Rank BT procedure based on the extended Krylov subspace method, that can handle large-scale models and significantly accelerate the EM stress analysis for any general interconnect or power grid structure. For the experimental evaluation, we first consider a general structure interconnect tree to demonstrate the generalizability of the proposed method and then we employ our method on the industrial IBM power grid benchmarks where the its scalability is shown. For the latter, we demonstrate that our method can achieve a speedup up to 238× over a standard transient analysis method and a speedup up to 15× over COMSOL, while exhibiting negligible error.

Aligned regenerated cellulose-based nanofluidic fibers with ultrahigh ionic conductivity and underwater stability for osmotic energy harvesting

The growing interest in biomass-based nanofluids has revealed flaws in large-scale manufacturing, customizable aligned nanostructures, and the weak interaction of structural components, resulting in low ionic conductivity, unsatisfactory long-term reliability underwater, and insufficient energy conversion efficiency. Herein, we present a bottom-up strategy integrating cellulose dissolution, orientation, regeneration, and densification to construct regenerated cellulose-based nanofluidic fibers (RCNFs) comprising a high weight content of acidified carbon nanotubes (40 %), aligned nanochannels (3–4 nm), and negatively charged surfaces (–3.05 mC m−2). Benefited from the synergistic alignment and spatial confinement of CNTs by the cross-linked cellulose network, the RCNFs realized a high underwater strength (29 MPa), unprecedentedly high ionic conductivity (0.07 S cm−1) at low salt concentrations (<0.001 M), and high long-term output power density (2.57 W m−2 over 43 days) in an artificial river water–seawater system. In a proof-of-concept experiment, customizable RCNF-based devices connected in series powered a calculator and LED lights at a 50-fold concentration gradient. This work can promote the application of regenerated cellulose in high-performance osmotic energy conversion systems.

Enhanced SOFC Cathode Performance Through Surface Modification of NdBa0.5Sr0.5Co2O5+δ Nanoparticles

The cathode materials fabrication with outstanding performance and stability at intermediate temperatures of 600–800℃ is required for the prospective mass production of solid oxide fuel cells (SOFCs). Infiltration is a potential method because it has proven successful in fabrication and cell performance enhancement. This study mainly focuses on the electrical conductivity and long-term reliability of cathode symmetric cells NdBa0.5Sr0.5Co2O5+δ (NBSC) fabricated by traditional solid-state reaction techniques. The electrical conductivity value of the cathode is in the range of 174–278 S.cm-1. Impedance analysis showed that the infiltration of 0.5M SDC on the NBSC cathode surface dramatically reduced the polarization resistance (Rp) between layers (cathode-electrolyte) from 3.32 Ω.cm2 to 1.82 Ω.cm2 at 600℃ or decreased by 45 % compared to NBSC cathode without 0.5M SDC infiltration. The enhanced stability of NBSC cathode specimens with 0.5M SDC infiltration (NBSC+0.5 M SDC) under SOFC operating conditions proves that samples with infiltration extend their lifetime. Compared to the NBSC cathode, the NBSC+0.5 M SDC cathode has better long-term stability with a lower RP value of 2.35 Ω.cm2. In the OPP range of 0.214-0.0027 atm at 800℃, the relatively tiny Rp value of the symmetrical cell is between 0.030 Ω.cm2 and 0.039 Ω.cm2, below the 0.15 Ω.cm2 suitable performance limit for solid oxide fuel cells.

Engineering Electrodes with Robust Conducting Hydrogel Coating for Neural Recording and Modulation.

Coating conventional metallic electrodes with conducting polymers has enabled the essential characteristics required for bioelectronics, such as biocompatibility, electrical conductivity, mechanical compliance, and the capacity for structural and chemical functionalization of the bioelectrodes. However, the fragile interface between the conducting polymer and the electrode in wet physiological environment greatly limits their utility and reliability. Here, a general yet reliable strategy to seamlessly interface conventional electrodes with conducting hydrogel coatings is established, featuring tissue-like modulus, highly-desirable electrochemical properties, robust interface, and long-term reliability. Numerical modeling reveals the role of toughening mechanism, synergy of covalent anchorage of long-chain polymers, and chemical cross-linking, in improving the long-term robustness of the interface. Through in vivo implantation in freely-moving mouse models, it is shown that stable electrophysiological recording can be achieved, while the conducting hydrogel-electrode interface remains robust during the long-term low-voltage electrical stimulation. This simple yet versatile design strategy addresses the long-standing technical challenges in functional bioelectrode engineering, and opens up new avenues for the next-generation diagnostic brain-machineinterfaces.

Development of Low-Residual-Stress Photosensitive Adhesive Materials for Wafer-Scale Microfluidic Device Fabrication

We have previously developed a photosensitive adhesive material that enables microfluidic channel structure formation and subsequent bonding to a cover with the aim of simplifying the process of wafer-scale microfluidic device fabrication. However, the bonding process and a subsequent curing process required heat treatment at 200 ℃ and 180 ℃, respectively, resulting in the generation of relatively high residual thermal stress. This may lead to delamination, warping, and cracking depending on the application environment. Therefore, in the present study, we designed a new material platform in which the patterning, bonding, and curing processes are based on ultraviolet (UV) reaction of polyfunctional acrylate, tackiness of epoxy resin, and UV/thermal reaction of epoxy resin in order to achieve low residual stress through low-temperature processing. Proof of concept was conducted through the evaluation of various physical properties of the system and found that the new type of photosensitive adhesive material, which bonded to a cover and cured at lower temperatures of 100 ℃ and 120 ℃, respectively, had a low residual stress of 10 MPa and good insulation reliability. This is a promising material for applications such as cooling devices for semiconductor chips, where long-term reliability is required.

Risk-aversion optimal hedging scenarios during droughts

The primary purpose of a water supply reservoir is to regular highly fluctuating streamflow for providing reliable water supplies. Reducing water shortage risk for impending droughts is a challenge task in real-time reservoir operation due to future inflow uncertainty. The main aim of this study is to propose risk-aversion optimal hedging scenarios during droughts, which is achieved by a two-stage approach. The water shortage probabilities of future lead times are analytically estimated first, then follows an optimization framework that simultaneously minimizing water shortage probabilities of future lead times and sustaining long-term water supply reliability. With an illustration application of the Nanhua Reservoir located in southern Taiwan, the results indicate that the proposed optimization framework provides an efficient hedging to reduce future water shortage probabilities and mitigate severe water shortages in real-time operation. The proposed optimal hedging scenarios outperforms the rule-curve-based current operation. Further improvements are noted for the time-varying rationing coefficient scenarios than the constant-coefficient scenario and the most favorable scenario is the scenario with the highest time-varying frequency. Using the storage to trigger hedging associated with estimated future lead-time water shortage probabilities as the objective functions, the proposed optimal hedging scenarios are not only risk aversion but also executable in real-time operation during droughts.

Improvement in the reliability of crystalline silicon solar cell interconnection by using Nickel Micro-Plating Bonding (NMPB) technology

It is popular to research promoting the light conversion efficiency of crystalline silicon solar cell photovoltaic (PV) modules. However, excellent light conversion efficiency does not mean it could maintain initial performance after long-term running. Long-term reliability of interconnection to assemble crystalline silicon solar cells in PV modules is critical to ensure that the device performs continually for up to 20 years. It is reported that most crystalline PV modules fail from corrosion and breakage of the interconnector with the solder joint. As a result, improvement of interconnection technology is highly necessary. Nickel (Ni) Micro-Plating Bonding (NMPB) is an innovative interconnection technology for crystalline silicon solar cells: copper ribbons bonded with lead or lead-free solder are replaced by copper wires bonded with Ni electroplating film. The NMPB interconnection provides key advantages: low temperature (55 °C) process, enhancement of reliability from strain and stress caused by high temperature, and coefficient of thermal expansion (CTE) mismatch between metal and silicon. Furthermore, the material of NMPB, Ni, possesses excellent corrosion resistance. High reliability was confirmed with about 1.9% degradation of output power for up to 1000 thermal cycling tests and 3.8% for 1000 h of damp heat tests in bare NMPB solar cells, while 64.7% degradation in thermal cycling tests and 23.0% in damp heat tests were confirmed in solder bonding solder cells.

Reliability of laser soldering using low melting temperature eutectic Sn Bi solder and electroless Ni-electroless Pd-immersion Au-finished Cu pad

The demand for flexible wearable devices/substrates with miniaturization and improved integration in microelectronic devices has intensified the research interest in low-temperature laser soldering processes as an alternative to conventional reflow soldering processes owing to their advantages, such as local heating, non-contact heating, and short bonding time. In this study, we compared and evaluated the reliability of laser soldered and conventional reflow soldered joints using representative low melting temperature eutectic Sn Bi solder and thin electroless Ni-electroless Pd-immersion Au (ENEPIG)-finished Cu pads. Laser soldering was performed using various laser powers (130, 150, and 170 W) and times (2 and 4 s). Furthermore, an aging test was performed at 110 °C for 2000 h to evaluate the long-term reliability of the soldered joints. The mechanical properties, including the top and cross-sectional views and fracture surfaces, of the soldered joints were analyzed by conducting shear tests after aging. During laser soldering, various intermetallic compounds (IMCs) were formed at the joints depending on the applied energy. The metallization layer and Cu reacted with Sn in the solder after different aging durations, and additional IMCs were formed and grown. After aging for 2000 h, the shear strength decreased, and the interfacial IMC thickness increased. As the aging time increased, the fracture mode changed from an initial ductile fracture to brittle fracture (between the solder and IMCs and/or between IMCs and the Cu pad). The reflow soldered joints exhibited stable shear strength, resulting in ductile fracture until aging for 500 h. However, the shear strength decreased sharply after aging for 1000 and 2000 h, and Bi-segregation was observed after aging for 1000 h, resulting in inferior long-term reliability. After laser soldering at 150 and 170 W for 4 s, the strength of the samples decreased sharply after aging for 1000 and 250 h, respectively, and Bi-segregation was observed after aging for 2000 h. The shear strength of the sample laser soldered at 170 W for 2 s gradually decreased with increasing aging time and maintained a stable shear strength until aging for 2000 h. Therefore, laser soldering at 170 W for 2 s was considered as the optimal condition for long-term reliability. • Soldering properties of laser soldered Sn-58Bi/Au/Pd/Ni-finished Cu joints evaluated. • Laser soldering results were compared with conventional reflow soldered joints. • Various IMCs were formed depending on laser power and irradiation time. • Laser conditions with low applied energy displayed superior long-term reliability. • Selection of the optimal laser conditions is crucial to ensure reliable solder joints.

Impact of Non-Accelerated Aging on the Properties of Parylene C

The polymer Parylene combines a variety of excellent properties and, hence, is an object of intensive research for packaging applications, such as the direct encapsulation of medical implants. Moreover, in the past years, an increasing interest for establishing new applications for Parylene is observed. These include the usage of Parylene as a flexible substrate, a dielectric, or a material for MEMS, e.g., a bonding adhesive. The increasing importance of Parylene raises questions regarding the long-term reliability and aging of Parylene as well as the impact of the aging on the Parylene properties. Within this paper, we present the first investigations on non-accelerated Parylene C aging for a period of about five years. Doing so, free-standing Parylene membranes were fabricated to investigate the barrier properties, the chemical stability, as well as the optical properties of Parylene in dependence on different post-treatments to the polymer. These properties were found to be excellent and with only a minor age-related impact. Additionally, the mechanical properties, i.e., the Young's modulus and the hardness, were investigated via nano-indentation over the same period of time. For both mechanical properties only, minor changes were observed. The results prove that Parylene C is a highly reliable polymer for applications that needs a high long-term stability.

Defect-Based Empirical Model for On-State Degradation in Sub-20-nm DRAM Periphery pFETs Under Arbitrary Condition

This work investigates the ON-state degradation under arbitrary stress conditions for periphery pFETs fabricated in the sub-20-nm DRAM technology. Three types of traps are identified, including the interface states, the oxide hole traps, and the oxide electron traps. By analyzing the time dependence, stress dependence, and lateral position, the generation mechanism for each type of trap is revealed, based on which a defect-based model was established. We proposed an effective model parameter extraction strategy and, thus, avoided overfitting. The predictive capability of the proposed model is further verified across the full bias regions at lower voltage conditions, including operating conditions. Finally, based on the model, the contributions of different types of traps to the degradation can be derived throughout the device’s entire lifetime. The work paves ways to link the defects to the device’s long-term reliability, which can be helpful for future process optimization and device/circuit co-optimization in DRAM peripheral circuits.

Preparation and thermal characterization of capric-myristic acid binary eutectic mixture with silver–antimony tin oxide and silver-graphane nanoplatelets hybrid-nanoparticles as phase change material for building applications

• Capric–Myristic acid (CA-MA) binary mixture is proposed for building applications. • Silver- Graphene nanoplatelets (Ag-GNP) (1% wt) was used as hybrid nanocomposites. • Melting and freezing temperature of CA-MA/ Ag-GNP (1% wt) are 18.7 °C and 15.7 °C. • The thermal conductivity of CA-MA/ Ag-GNP (1% wt) was enhanced by 18.52 %. • The prepared CA–MA/Ag-GNP (1% wt) mixture are suitable for building applications. The capric-myristic acid binary eutectic mixture (CA-MA) was prepared as phase change material (PCM) for building applications; later, novel hybrid-nanocomposites of silver–antimony tin oxide (Ag-ATO) and silver-graphane nanoplatelets (Ag-GNP) were added with CA-MA with a weight percentage of 1 and 2 respectively to form a hybrid-nanocomposite PCMs (HNCPCMs). The chemical and thermal characterization of pure CA-MA and HNCPCMs showed that their stability is significant for building applications. The melting temperature (T m ) and freezing temperature (T f ) of pure CA-MA synthesised are 18.15 °C and 16.00 °C, respectively, with melting latent heat (H m ) and freezing latent heat (H f ) of 158.75 J/g and 158.07 J/g, respectively. An HNCPCM of CA-MA/Ag-GNP (1 % wt) shows an improved melting thermal conductivity of 18.52 %, with negligible deviation in melting-freezing temperature and latent heat. The proposed CA-MA/Ag-GNP (1% wt) has significant thermal, chemical, and long-term cycling reliability, making it a promising material for building applications.