MEMS Piezoelectric Energy Harvester Powered Wireless Sensor Module Driven by Noisy Base Excitation

Despite recent advances in MEMS vibration energy harvesting and ultra-low power wireless sensors, designing a wireless sensor system entirely powered by a single MEMS device under noisy base excitation has remained a challenge. This paper presents a wireless sensor system co-integrated with a single MEMS piezoelectric vibration energy harvester chip excited by band-limited large amplitude noisy vibration characteristic of an automotive application. The use of soft stoppers in the MEMS package enables the harvesters to operate at an excitation level of 10 g(rms). A custom thick AlN (Aluminum Nitride) piezoelectric process is employed to fabricate the MEMS harvesters with a single MEMS chip generating 179 μW rectified power under these excitation conditions. A low-power wireless sensor module and a receiver module were also designed and demonstrated in this work. Experiments show that the wireless sensor module can be powered solely by the MEMS energy harvester commencing from the cold state. Successful wireless data transmission and receival of sensor data packets are recorded under representative conditions

Exploring the feasibility of a classroom-based vocabulary intervention for mainstream secondary school students with language disorder

Vocabulary knowledge has been shown to be a predictor of academic success, posing a challenge for children and young people with language disorder. Language disorder can persist into adolescence and yet there is limited evidence on how to support the vocabulary skills of adolescents with language disorder in a mainstream setting. This article describes an experimental study aimed at investigating the feasibility of a whole-class approach to increase the understanding and use of curriculum vocabulary in adolescents with language disorder. Ten curriculum words were taught by the science teacher using a phonological-semantic approach, and 10 matched same-topic words were taught using routine teaching practice. Progress was made post-intervention in word knowledge of both low-frequency experimental and control words, with significantly greater change in knowledge of the experimental words. Most students, and the teacher, viewed the phonological-semantic word-learning approach favourably

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Realisation of high temperature electronics packaging technology for sensor conditioning and processing applications

The requirement to install electronic power and control systems in high temperature environments in aeroengines and in down-well exploration has posed a challenge to the traditional limit of 125°C of electronics systems. The leap in operating temperature to above 200°C in combination with high pressures, vibrations and potentially corrosive environments means that different semiconductors, passives, circuit boards and assembly processes will be needed to fulfil target performance specifications. Silicon on Insulator (SOI) device technology has been shown to be capable of functioning satisfactorily at operating temperatures of >200°C. Most of the applications to date have required performance for short times (<2,000 hours) at the highest operating temperatures of up to 225°C in down-well drilling applications. There is interest in extending the endurance of high temperature electronics into aero-engine and other applications where a minimum 20 year operating life is stipulated. Most of the reliability data on the high temperature endurance of the integrated circuit is generated with little consideration of the packaging technologies, whilst most of the reliability data pertinent to high temperature packaging technologies uses test pieces, which limits any conclusions relating to long term electrical performance. This paper will present results of studies on high temperature packaging technologies relevant to signal conditioning and processing functions for sensors in down-well and aero-engine applications. Different die attach and wire bond options have been included in the study and the performance of several functional blocks on a high temperature SOI device has been tracked over the endurance tests which have lasted for >11,000 hours at 250°C. Degradation phenomena such as thermal migration and material deterioration due to high temperature exposure in air and inert atmospheres will be described. An assessment of the availability of high temperature materials and components to meet long term requirements for operation at 250°C will be presented

High Temperature Endurance of Packaged SOI Devices for Signal Conditioning and Processing Applications

Silicon on Insulator (SOI) device technology is fulfilling a niche requirement for electronics that functions satisfactorily at operating temperatures of >200°C. Most of the reliability data on the high temperature endurance of the devices is generated on the device itself with little attention being paid to the packaging technology around the device. Similarly, most of the reliability data generated on high temperature packaging technologies uses testpieces rather than real devices, which restricts any conclusions on long term electrical performance. This paper presents results of high temperature endurance studies on SOI devices combined with high temperature packaging technologies relevant to signal conditioning and processing functions for sensors in down-well and aero-engine applications. The endurance studies have been carried out for up to 7,056 hours at 250°C, with functioning devices being tested periodically at room temperature, 125°C and 250°C. Different die attach and wire bond options have been included in the study and the performance of multiplexers, transistors, bandgap voltage, oscillators and voltage regulators functional blocks have been characterised. This work formed part of the UPTEMP project which was set-up with support from UK Technology Strategy Board and the EPSRC. The project brought together a consortium of end-users (Sondex Wireline and Vibro-Meter UK), electronic module manufacturers (GE Aviation Systems Newmarket) and material suppliers (Gwent Electronic Materials and Thermastrate Ltd) with Oxford University - Materials Department, the leading UK high temperature electronics research centre

End of life failure modes for packaged SOI devices for signal conditioning and processing applications

Silicon on Insulator (SOI) device technology has been shown to be capable of functioning satisfactorily at operating temperatures of >200 C. Most of the applications to date have required performance for short times (<2,000 hours) at the highest operating temperatures of up to 225 C in down-well dulling applications. There is interest in extending the endurance of high temperature electivnics into aero-engine and other applications where a minimum 20 year operating life is stipulated. In order to gain confidence in high temperature electronics that can meet this requirement, accurate reliability data are needed and end of life failure modes need to be identified. Most of the reliability data on the high temperature endurance of the integrated circuit is generated with little consideration of the packaging technologies, whilst most of the reliability data pertinent to high temperature packaging technologies uses test pieces rather than devices, which limits any conclusions relating to long term electrical performance. This paper presents results of temperature storage and cycling endurance studies on SOI devices combined with high temperature packaging technologies relevant to signal conditioning and processing functions for' sensors in down-well and aero-engine applications. The endurance studies have been cariied out for up to 11, OSS hours at 250°C, with functioning devices being tested periodically at room temperature, 125°C and 250° C and rapid thermal cycling from -40 C to +225 C. Different die attach and wire bond options have been included in the study and the performance of several functional blocks on the SOI device has been tracked over the endurance tests. The failure modes observed on completion of the endurance tests include die cracking and deterioration of the device bond pads accelerated due to degradation of some die attach materials. The routes to achieving stable long term performance of packaged devices at temperatures of250°C will be outlined

Assessment of MEMS vibration energy harvesting for high temperature sensing applications

Distributed electronics for improving the accuracy of sensing in harsh high temperature environments, such as aero-engine and down-well is a growing field, where reduced power input requirements in cabling and batteries is viewed a key enabler for accelerating the adoption of high temperature electronics. Although batteries are available that can operate up to 200°C, they offer limited life at high temperatures and are bulky, increasing the costs of deployment and maintenance. Cabling also adds weight and takes up space in limited access applications. Energy harvesting in-situ offers the opportunity to make a step change in the design of high temperature electronics modules and in expanding their possible range of applications; for example, in sensor systems for combustor and turbine monitoring in aero-engines. This paper covers an assessment of MEMS vibration energy harvesting technology for high temperature sensing applications. MEMS devices based on the principle of parametric resonance, using AlN on Silicon have been designed and fabricated, along with sourcing of high temperature components for rectification, impedance matching and energy storage. The MEMS devices have been packaged into ceramic chip carriers and measured for energy output from a random vibration profile representative of an aerospace application. The measured output from the MEMS vibration energy harvester is capable of providing sufficient power to be of interest for autonomous sensing applications. This paper reports on the performance of the MEMS vibration energy harvesting devices and their associated circuitry at room temperature and at temperatures of up to 150°C. The challenges remaining to develop robust energy harvesting devices that could be applied in aero-engine, down-well and other high temperature applications are described. This work has been carried out under the Innovate UK supported project HI-VIBE, in a collaboration between GE Aviation Systems - Newmarket and the University of Cambridge

Design and assembly of high temperature distributed aero-engine control system demonstrator

This paper covers the development of a distributed high temperature electronics demonstrator for integration with sensor elements to provide digital outputs that can be used by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aircraft engine. This distributed electronics demonstrator eliminates the need for the FADEC or EHMS to process the sensor signal, which will assist in making the overall system more accurate and efficient in processing only digital signals. This will offer weight savings in cables, harnesses and connector pin reduction. The design concept was to take the output from several on-engine sensors, cany out the signal conditioning, multiplexing, analogue to digital conversion and data transmission through a serial data bus. The unit has to meet the environmental requirements of DO-160 with the need to operate at 200°C, with short term operation at temperatures up to 250°C. The work undertaken has been to design an ASIC based on 1.0μm Silicon on Insulator (SOI) device technology incorporating sensor signal conditioning electronics for sensors including resistance temperature probes, strain gauges, thermocouples, torque and frequency inputs. The ASIC contains analogue multiplexers, temperature stable voltage band-gap reference and bias circuits, ADC, BIST, core logic, DIN inputs and two parallel ARINC 429 serial databuses. The ASIC was tested and showed to be functional up to a maximum temperature of 275° C. The ASIC has been integr ated with other high temperature components including voltage regulators, a crystal oscillator, precision resistors, silicon capacitors within a hermetic hybrid package. The hybrid circuit has been assembled within a stainless steel enclosure with high temperature connectors. The high temperature electronics demonstrator has been shown to operate from -4(fC to +250°C. This work has been carried out under the EU Clean Sky HIGHTECSproject with the Project being led by Turbomeca (Fr) and carried out by GE Aviation Systems (UK), GE Research -Munich (D) and Oxford University (UK)

Design and assembly of high temperature distributed aero-engine control system demonstrator

This paper covers the development of a distributed high temperature electronics demonstrator for integration with sensor elements to provide digital outputs that can be used by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aircraft engine. This distributed electronics demonstrator eliminates the need for the FADEC or EHMS to process the sensor signal, which will assist in making the overall system more accurate and efficient in processing only digital signals. This will offer weight savings in cables, harnesses and connector pin reduction. The design concept was to take the output from several on-engine sensors, cany out the signal conditioning, multiplexing, analogue to digital conversion and data transmission through a serial data bus. The unit has to meet the environmental requirements of DO-160 with the need to operate at 200°C, with short term operation at temperatures up to 250°C. The work undertaken has been to design an ASIC based on 1.0μm Silicon on Insulator (SOI) device technology incorporating sensor signal conditioning electronics for sensors including resistance temperature probes, strain gauges, thermocouples, torque and frequency inputs. The ASIC contains analogue multiplexers, temperature stable voltage band-gap reference and bias circuits, ADC, BIST, core logic, DIN inputs and two parallel ARINC 429 serial databuses. The ASIC was tested and showed to be functional up to a maximum temperature of 275° C. The ASIC has been integr ated with other high temperature components including voltage regulators, a crystal oscillator, precision resistors, silicon capacitors within a hermetic hybrid package. The hybrid circuit has been assembled within a stainless steel enclosure with high temperature connectors. The high temperature electronics demonstrator has been shown to operate from -4(fC to +250°C. This work has been carried out under the EU Clean Sky HIGHTECSproject with the Project being led by Turbomeca (Fr) and carried out by GE Aviation Systems (UK), GE Research -Munich (D) and Oxford University (UK)

Morphological and morphometric analysis of the distal branches of the rat brachial plexus

The rat brachial plexus has gained interest recently in neuro-regenerative research due to the advancement of neurosurgical equipment and techniques, but moreover in that it provides a model that can closely resemble the common peripheral nerve injuries seen in humans. The aim of this study was to provide a systematic baseline quantification for fibre type and morphology of the major terminal nerve branches of the rat brachial plexus (radial, ulnar and median) at four surgically accessible sites, through the forelimb. We applied a microstructural and immunohistological analysis of 12 rat brachial plexuses using three forms of micro-visualisation: electron microscopy; whole mount; and immunohistology. The three distal nerves studied showed a similar patterning in terms of the number and size of myelinated fibres, with all proportionally decreasing when moving distally. The fibre types of both the median and ulnar nerve appeared to be homogenously mixed throughout their trajectory, while the radial nerve had a more distinct patterning, especially distal to the elbow, with the entire nerve’s main branch appearing to consist of sensory fibres only. Our microstructural analysis of the rat brachial plexus provides important normative reference data for future peripheral nerve research using the forelimb of the rat.Griffith Health, School of Nursing and MidwiferyFull Tex