Efficient Organic and Inorganic Hybrid Interlayer for High Performance Inverted Red Cadmium-free Quantum Dot Light-Emitting Diodes

The efficiency and device lifetime of quantum dot light-emitting diodes (QLEDs) devices suffer due to charge unbalance issue resulting from excess electron injection from ZnO electron transport layer (ETL) to...

On the Energy Performance of Iridium Satellite IoT Technology

Most Internet of Things (IoT) communication technologies rely on terrestrial network infrastructure. When such infrastructure is not available or does not provide sufficient coverage, satellite communication offers an alternative IoT connectivity solution. Satellite-enabled IoT devices are typically powered by a limited energy source. However, as of this writing, and to our best knowledge, the energy performance of satellite IoT technology has not been investigated. In this paper, we model and evaluate the energy performance of Iridium satellite technology for IoT devices. Our work is based on real hardware measurements. We provide average current consumption, device lifetime, and energy cost of data delivery results as a function of different parameters. Results show, among others, that an Iridium-enabled IoT device, running on a 2400 mAh battery and sending a 100-byte message every 100 min, may achieve a lifetime of 0.95 years. However, Iridium device energy performance decreases significantly with message rate.

Die-Level Vacuum Packaging of Mems Devices with Non-Evaporating Getters

In this article original method of vacuum packaging in ceramic package 5142.48-A with non-evaporating getter inside is described. Some MEMS devices such as gyroscopes, accelerometers and resonators often require high and stable vacuum for operational capability. It is known two main approaches to the vacuum packaging of MEMS devices: hermetization on the wafer level and on the die level. Die-level vacuum packaging can be implemented by sealing the die in ceramic package providing excellent hermeticity with sufficiently low leak rate. However, because of outgassing from materials of the package it is difficult to achieve stable vacuum over all MEMS device lifetime. To prevent vacuum degradation it is necessary to use special materials that can remove active gases from the package by chemical sorption named getters. In this work tablet-shaped non-evaporating getter with thickness of 0.7 mm made of titan-vanadium alloy with activation temperature near 525 °C was used. For the vacuum packaging workflow new special vacuum chamber is designed. It may contain four MEMS devices simultaneously. During the process of getter activation heating was provided by halogen lamps G12 35 Wplaced over the caps of the ceramic packages with a little gap. It is defined that in deep vacuum full power of one lamp can heat the cap of the package to the temperature more than 600 °C. Probable overheating is excluded by means of the newly-designed programmable device — power switch, which can maintain required temperature in automatic mode for the necessary time. Temperature control is realized by no-contact pyrometrical method. During the experiment all necessary parameters providing specified temperature profile of the process were determined. Efficiency of the developed vacuum packaging workflow is successfully confirmed by the high and stable Q-factor of fabricated MEMS gyroscopes.

Solution-Processed Chloroaluminum Phthalocyanine (ClAlPc) Ammonia Gas Sensor with Vertical Organic Porous Diodes

In this research work, the gas sensing properties of halogenated chloroaluminum phthalocyanine (ClAlPc) thin films were studied at room temperature. We fabricated an air-stable ClAlPc gas sensor based on a vertical organic diode (VOD) with a porous top electrode by the solution process method. The surface morphology of the solution-processed ClAlPc thin film was examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The proposed ClAlPc-based VOD sensor can detect ammonia (NH3) gas at the ppb level (100~1000 ppb) at room temperature. Additionally, the ClAlPc sensor was highly selective towards NH3 gas compared to other interfering gases (NO2, ACE, NO, H2S, and CO). In addition, the device lifetime was tested by storing the device at ambient conditions. The effect of relative humidity (RH) on the ClAlPc NH3 gas sensor was also explored. The aim of this study is to extend these findings on halogenated phthalocyanine-based materials to practical electronic nose applications in the future.

A Systematic Review of Compliant Mechanisms as Orthopedic Implants

Currently available motion-preserving orthopedic implants offer many advantages but have several limitations to their use, including short device lifetime, high part count, loss of natural kinematics and wear-induced osteolysis and implant loosening. Compliant mechanisms have been used to address some of these problems as they offer several potential advantages - namely wear reduction, reduced part count, and the ability to achieve complex, patient-specific motion profiles. This article provides a systematic review of compliant mechanisms as orthopedic implants. Based on the PRISMA guidelines for an efficient review, this work identified fourteen implantable orthopedic devices that seek to restore anatomical motion by utilizing mechanical compliance. From reviewing these implants and their results, advantages and consequences for each are summarized. Trends were also identified in how these devices are capable of mitigating common challenges found in orthopedic design. Design considerations for the development of future compliant orthopedic implants are proposed and discussed.

Single emission spectrum measurement enables control of organic LED emission zone giving ultralong device lifetime

Device optimization of light-emitting diodes targets the most efficient conversion of electrically injected charges into emitted light. Where charges recombine and where light is emitted from is known as the emission zone. Determining its form is key to better understanding the physical processes determining device performance. However, a thorough measurement study has not been shown. Here we present an accessible technique to visualize the emission zone in unprecedented detail at all luminescing current densities. Only a single emission spectrum must be measured (at normal direction to the device layers with no additional optics) and compared with the simulated emission spectrum. This method allows physical understanding based, instead of speculative, optimisation of LED device architectures. We demonstrate its impact by examining the device structure – emission zone – lifetime relationships of a thermally activated delayed fluorescence OLED to achieve an ultralong 4500 hour T95 lifetime at 1000 cd/m2 with 20% external quantum efficiency.