Abstract

A dielectric elastomer actuator (DEA) is a capacitor with an elastomer as dielectric, sandwiched between two complaint electrodes. An electric potential difference applied across the electrodes results in an electric field that creates lateral motion in the device which can be used to perform mechanical work. However, both the dielectric as well as the electrodes needs to be mechanically compliant. In order to achieve high stretchability, carbon nanotube (CNT) based thin films are used as electrodes to maintain conductance even at large mechanical strains. These electrodes are typically fabricated using spray coating or filter transfer method and resemble a perforated electrode under high magnification. Hence, there can be loss of field and stray capacitance when multiple layers of carbon nanotube based electrodes are used. This paper presents theoretical modelling and finite element analysis (FEA) simulations to …

Abstract

A capacitive pressure sensor consists of a movable diaphragm which causes change in capacitance for an applied pressure. In order to achieve high sensitivity, a thin diaphragm of large area is employed with a small separation gap. This introduces non-linearity, decreases the dynamic range and increases the size of the sensor. Thus, an optimum sensor design is necessary to balance these trade-offs. This paper presents theoretical modeling and numerical simulations on various performance parameters like diaphragm deflection, change in capacitance, mechanical and capacitive sensitivities and nonlinearity of a clamped and normal mode elliptical capacitive pressure sensor for 0 – 8 kPa operating pressure range. This analysis can form the basis for compact modelling (CM) of circular and elliptical capacitive pressure sensors for simulation with large scale circuits. In all the designs of elliptical and circular …

Abstract

With recent advancements in the field of wearable devices based on Internet of Things (IoT), the concept of flexible and stretchable electronic systems has become increasingly significant. Although decades of dimensional scaling have led to the miniaturization of the traditional complementary metal oxide semiconductor-(CMOS-) based electronic components, they still remain mechanically rigid and brittle. These rigid devices can be mounted on flexible PCB substrates to obtain a certain degree of flexibility; however, this technique cannot lead to truly body conformal electronic systems. Thus, research teams around the world have been looking at various ways of obtaining completely flexible electronic components at the device level itself. These efforts include various processes to thin down silicon chips to make them flexible or development and use of flexible and stretchable substrate materials to fabricate electronic devices. The thinning down process for traditional silicon-based electronic chips can be performed before or after the complete transistor fabrication process [1]. These approaches are referred to as “device first” approach or “device last” approach. In case of the device last approach, thin films of single crystal silicon are transfer printed to a flexible substrate and processed further to fabricate CMOS circuitry [2, 3]. However, in this approach, many high-temperature steps have to be avoided due to the limited thermal stability of the flexible substrate, leading to a suboptimal circuit. In case of the device first approach, the circuits are made on the silicon substrate using state-of-the-art CMOS processes as usual. After completion of the …

Abstract

Micropumps are one of the most important parts of a microfluidic system. In particular, for biomedical applications such as Lab-on-Chip systems, micropumps are used to transport and manipulate test fluids in a controlled manner. In this paper, a low-cost, structurally simple, piezoelectrically actuated micropump was simulated and fabricated using poly-dimethylsiloxane (PDMS). The channels in PDMS were fabricated using patterned SU-8 structures. The pump flow rate was measured to be 9.49 μL/min, 14.06 μL/min and 20.87 μL/min for applied voltages of 12 V, 14 V and 16 V respectively. Further, we report finite element analysis (FEA) simulation to confirm the operation of the micropump and compare favorably the experimentally obtained flowrate with the one predicted by simulation. By taking these flow rates as a reference, the chamber pressure was found to be 1.1 to 1.5 kPa from FEA simulations.

Abstract

Energy consumption has dramatically increased in the residential building sector over the past few years. Many researchers today are interested not only in designing energy-efficient buildings but also in evaluating the actual building performance and managing operations for delivering the design intent. Monitoring building performance using currently available sensors and mobile applications poses challenges in terms of cost and standardization. This paper presents a new approach to make sensors affordable and inter-operable by designing open-source hardware and using well-established standards for data communication and storage, thereby making energy monitoring ubiquitous and affordable in the residential sector. The proposed solution uses low-power loggers, Bluetooth Low Energy wireless communication version 4 for data transfer from loggers to mobile phones for further transfer to cloud, oneM2M standard to ensure interoperability, and NGSI-LD for data management.

Abstract

The design and fabrication of a rolled dielectric elastomer actuator is described and the parametric dependence of the displacement and blocked force on the actuator geometry, elastomer layer thickness, voltage, and number of turns is analyzed. Combinations of different elastomers and carbon nanotube electrodes are investigated and optimized to meet performance characteristics appropriate to tactile display applications, namely operation up to 200 Hz with a combination of a 1 N blocked force and free displacement of 1 mm, all within a volume of less than 1 cm3. Lives in excess of 50 000 cycles have been obtained. Key to meeting these objectives is control of the multilayering fabrication process, the carbon nanotube electrode concentration, the selection of a soft elastomer with low viscous losses, and a proof‐testing procedure for enhancing life cycle reliability.

Abstract

Nearly sixty years back when Jack Kilby built the first integrated circuit (IC), it was also the beginning of today's advanced and matured complementary metal oxide semiconductor (CMOS) technology whose arts and science of miniaturization has enabled Moore's Law to double up the number of devices in a given area in every two years. It has also been possible because CMOS technology has consistently adopted new materials and processes. High performance (data processing speed in computational devices), energy efficiency (for portable devices) and ultra-large-scale-integration (ULSI) density - all these features have been added to every major technology generation in additive manner. As we go forward and embrace Internet of Everything (IoE) where people, process, device and data are going to be seamlessly connected, we may want to ask ourselves a few fundamental questions about the future

Abstract

Thermoelectric generators (TEGs) are interesting energy harvesters of otherwise wasted heat. Here, a polymer‐assisted generic process and its mechanics to obtain sputtered thermoelectric (TE) telluride material‐based 3D tubular structures with unprecedented length (up to seamless 4 cm and further expandable) are shown. This length allows for large temperature differences between the hot and the cold ends, a critical but untapped enabler for high power generation. Compared with a flat slab, better area efficiency is observed for a rolled tube and compared with a solid rod architecture, a rolled tube uses less material (thus making it lightweight and cost effective) and has competitive performance advantage due to a smaller contact area. It is also shown that a tubular architecture thermopile‐based TEG is able to generate up to 5 μW of power (eight pairs of p‐ and n‐type thermopiles) through a temperature …