Plessey Semiconductors Ltd.
Plessey Semiconductors Ltd.
Ellis J.,Plessey Semiconductors Ltd. |
Pickard G.,Plessey Semiconductors Ltd.
Annual IEEE Semiconductor Thermal Measurement and Management Symposium | Year: 2017
A method for determining the thermal resistance of high power LEDs is described. Unlike more complicated systems, this method simply uses a fast pulse to determine the junction temperature under actual operating currents, combined with a conventional thermocouple to measure the mounting face temperature. The literature can be somewhat confusing in describing the thermal resistance of an LED. Often an 'apparent' thermal resistance is determined from the input power alone, ignoring the optical power output. This can provide a correct junction temperature as a guideline under a given condition. However, the real thermal resistance, which may be about twice as high as the apparent thermal resistance, is of little use unless the exact output power of the LED is known, so that the real heat dissipated can be determined. This is dependent on the operating current, temperature, and where the LED is on its longevity curve, and can also be affected by the light fitting as well. Therefore, it is necessary to model these LED effects which correctly describes the light output under real conditions. © 2017 IEEE.
Rae K.,University of Strathclyde |
Foucher C.,University of Strathclyde |
Guilhabert B.,University of Strathclyde |
Islim M.S.,University of Edinburgh |
And 9 more authors.
Optics Express | Year: 2017
Red-, orange-, and green-emitting integrated optoelectronic sources are demonstrated by transfer printing blue InGaN µLEDs onto ultra-thin glass platforms functionally enhanced with II-VI colloidal quantum dots (CQDs). The forward optical power conversion efficiency of these heterogeneously integrated devices is, respectively, 9%, 15%, and 14% for a blue light absorption over 95%. The sources are demonstrated in an orthogonal frequency division multiplexed (OFDM) visible light communication link reaching respective data transmission rates of 46 Mbps, 44 Mbps and 61 Mbps. © 2017 Optical Society of America.
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: SC5-12a-2014 | Award Amount: 6.20M | Year: 2015
The goal of INREP is to develop and deploy valid and robust alternatives to indium (In) based transparent conductive electrode materials as electrodes. In-based materials, mainly ITO, are technologically entrenched in the commercial manufacture of components like LEDs (both organic and inorganic), solar cells, touchscreens, so replacing them with In-free transparent conducting oxides (TCOs) will require holistic approach. The INREP philosophy is to meet this challenge by addressing the whole value chain via an application focused research programme aiming at developing tailor made solutions for each targeted application. This programme will produce a complete evaluation of the relevant properties of the proposed TCOs, including the impact of deposition technique, and by doing so, devise optimum processes for their application in selected, high value application areas. The selected application areas are organic and inorganic light emitting diodes (LEDs), solar cells and touchscreens. The physical properties of interest are the transparency, electrical conductivity, work function, texture, and chemical and thermal stability. To reach its overall goal, INREP brings together industrial and academic experts in TCOs, the technology and processes for their deposition and their applications in a concerted research programme that will result in the creation of TCOs and deposition technologies with the optimum opto-electrical properties suitable for the economic and safe manufacture of the specified photonic or opto-electronic components. The approach will include life cycle assessments of the environmental impact of the developed TCO materials and of their formation technologies over the entire period from application in manufacturing, throughcomponent operation into waste management.
Agency: GTR | Branch: Innovate UK | Program: | Phase: Feasibility Study | Award Amount: 111.95K | Year: 2014
The objective of this project is to enhance vehicle safety systems through the creation of an automotive driver heart-rate sensor system that produces data of sufficient quality and consistency that it can be used to monitor driver alertness and well-being. Real time analysis of such data will enable the monitoring system to take early action to prevent a driver from falling asleep at the wheel and in the case of commercial vehicle operations, transmit the data over a wireless network to a control centre for automated monitoring of driver well-being. Based on a technology acquired from the University of Sussex, Plessey Semiconductors has developed a fully patented Electrical Potential Integrated Circuit (EPIC) Sensor which can measure electrophysiology signals without direct skin contact, skin preparation or conductive gels. Nottingham Trent University has developed a number of material technologies which allow the creation of conductive and non-conductive patches and connections within a piece of knitted fabric. These materials can form part of a remote electrode for the EPIC sensor, and thus provide a unique form factor for enhanced data acquisition and vehicle design. .
Connor S.,Plessey Semiconductors Ltd.
Sensors (Peterborough, NH) | Year: 2011
The electric potential integrated circuit (EPIC) sensor, an extremely robust solid-state electrometer with such high input impedance that it is close to being a perfect voltmeter, is presented. The electrode is protected by a capping layer of dielectric material to ensure that the electrode is isolated from the body being measured. The device is AC coupled with a lower corner frequency (-3dB) of a few tens of MHz and an upper corner frequency above 200 MHz. The device in single-ended mode can be used to read electric potential. The size of the electrode is somewhat arbitrary and depends on the input capacitance required for a particular application. The input capacitance can be driven as low as 10 -17 F with the input resistance being boosted to values up to around 10 15, thus keeping the interaction with the target field to an absolute minimum and ensuring that all currents are small displacement currents only.
Trindade A.J.,University of Strathclyde |
Guilhabert B.,University of Strathclyde |
Xie E.Y.,University of Strathclyde |
Ferreira R.,University of Strathclyde |
And 10 more authors.
Optics Express | Year: 2015
We report the transfer printing of blue-emitting micron-scale light-emitting diodes (micro-LEDs) onto fused silica and diamond substrates without the use of intermediary adhesion layers. A consistent Van der Waals bond was achieved via liquid capillary action, despite curvature of the LED membranes following release from their native silicon growth substrates. The excellence of diamond as a heat-spreader allowed the printed membrane LEDs to achieve optical power output density of 10 W/cm2 when operated at a current density of 254 A/cm2. This high-currentdensity operation enabled optical data transmission from the LEDs at 400 Mbit/s. © 2015 Optical Society of America.
Mukherjee S.,Plessey Semiconductors Ltd |
Breakspear R.,Plessey Semiconductors Ltd |
Connor S.D.,Plessey Semiconductors Ltd
Proceedings - Wireless Health 2012, WH 2012 | Year: 2012
This paper describes a technique for non-contact measurement of cardiac signals (ECG) from the driver of a car, with a wireless interface, thus allowing continuous monitoring of driver health. The system employs an ultra high impedance solid state electric field sensor-lectric Potential Integrated Circuit (EPIC) -developed by Plessey Semiconductors Ltd and the University of Sussex . Recent developments in both technology and understanding have resulted in a reliable technique for measuring ECG through clothing by means of sensors embedded in the driver's seat. A Bluetooth interface enables transmission of the data to a monitoring system, either in-car or on a mobile device such as a smart phone or tablet. The data can be monitored in real time", or subsequently sent over mobile or cloud computing networks to a remote server for analysis.
Agency: GTR | Branch: Innovate UK | Program: | Phase: Collaborative Research & Development | Award Amount: 343.77K | Year: 2013
Existing light emitting diodes (LEDs) do not emit light directionally, so in many applications not all photons are coupled into the optical system and result in wasted energy. This is notably true in image projection systems (a US$3B annual market) which require bigger, much brighter LEDs to replace inefficient discharge lamps. The aim of this project is to advance the development of new large area, high brightness InGaN LEDs with highly directional emission and capable of operating at high electrical power density to achieve the high on-screen lumens needed for advanced digital projectors. The innovation will involve realising such LEDs on Silicon substrates, the incorporation of novel nanostructures by cost effective methods to direct the light output, and wafer bonding to thermally conducting substrates to address the heat extraction problem. The new LEDs will also be tested in a novel projector design that requires multiple highly directional LEDs, to expand market opportunities.
Agency: GTR | Branch: Innovate UK | Program: | Phase: European | Award Amount: 183.17K | Year: 2013
Agency: GTR | Branch: Innovate UK | Program: | Phase: Procurement | Award Amount: 42.00K | Year: 2016
Plessey Semiconductors will be developing a single-arm ECG monitor aimed primarily at sports monitoring applications, but also with uses in other fields such as home health. Using its award- winning EPIC sensor in conjunction with knitted electrodes developed by Nottingham Trent University as part of a previous Innovate UK project, an armband will be produced for testing by Loughborough University and McClaren Applied Technologies.