Poling of VDF/TrFe copolymers using a step-wise method

A new poling technique is presented, in which a series of five consecutive pulses of electric field, and with successively increasing strength is applied between the two electrodes of 65/35 VDF/TrFE copolymer based sensor. Between each pulse, the applied electric field is reduced to zero (short circuit). This allows deformations and space charges to be relax, resulting in more homogeneous electric field distribution with less risk for an electric breakdown. It is conducted at room temperature and is compatible with semiconductor technology. This step-wise poling technique is characterised by a low breakdown rate and yields a high pyroelectric coefficien

An integrated charge amplifier for a pyroelectric sensor

This paper presents an integrated charge amplifier that measures a small charge. This charge is generated by a pyroelectric detector. The charge amplifier consists of a single-stage c-annon source configuration with a passive feedback network. The charge amplifier has a bandwidth of 700 kHz and an output noise voltage of 20 nV Hz 1/2 at 1 kHz. A 2×2 integrated pyroelectric sensor based on VDF/TrFE copolymer has been realized. The voltage response of this sensor-amplifier is reported

Laser growth of microelectronic materials

SIGLEAvailable from British Library Document Supply Centre- DSC:DX81726 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

PVDF sensors with low-temperature bonding techniques

The performances of poly-vinylidene fluoride (PVDF) thin-film infrared sensors with alternative bonding methods are presented in comparison with a more established method. A responsivity of 25 V (W cm−2)−1 is achieved using a commercially available acrylic adhesive. This method removes the requirement of raised temperature treatment of the PVDF thin-film material, which is prone to thermal damage at relatively low temperatures

A Cost-Effective Image Sensor System for Transport Applications Utilising a Miniature CMOS Single Chip Camera

The availability of a range image processing systems has made automatic traffic image analysis a viable proposition. The industrial take-up of image processing technology for traffic monitoring and control has been slow. One reason can be attributed to the high costs generally associated with digital image processing systems. Recent advances in digital computer and solidstate camera technology have resulted in falling equipment costs on the one hand and dramatic increase in performance on the other. This paper examines some of the methods and strategies adopted by the authors in applying video imaging technology to traffic analysis. A custom hardware solution is presented. The design methodology and system architecture is described

Application of a conductive polymer to self-absorbing ferroelectric polymer pyroelectric sensors

This paper presents application of a conductive polymer to a self-absorbing pyroelectric sensor. The pyroelectric sensor is a free standing thermal infrared detector. It consists of a conductive polymer (PEDT/PSS) as an absorber layer and front electrode, a PVDF film as the pyroelectric material and a Ni–Al metal film as a reflector layer and rear electrode. Theoretical analysis of the infra red absorptivity of this structure shows that a selective, self-absorbing pyroelectric sensor with an absorptance of up to 90% is feasible. The conductive polymer, PEDT/PSS with added organic binders, is coated on PVDF film using both spin-coating and solution-casting techniques. The deposition technology of the conductive polymer is shown to be a non-critical process with a high reproducibility and compatible with PVDF film. The measured response of this PVDF pyroelectric sensor is shown to be 10 times higher than that of a commercially available PVDF film with thin nickel aluminium front and back electrodes

A MINIMAL JERK PROSTHESIS CONTROL SYSTEM

Efficient prosthesis control is dependant on the user’s ability to control the desired movements of the prosthesis. Observed manifestations of jerk on a complete arm prosthesis can lead to difficulty in performing controlled movements, especially under load on gravity assisted downward movements. The application of so called soft start and soft stop routines for controlling the velocity profile of the prosthesis joint through its rotational movement can go some way to reducing this effect. It is proposed that an adaptive velocity control system can be applied to the same prosthesis under the same test conditions and reduce the discernible jerk considerably. This adaptive system monitors the change is angular velocity thus controlling the second and third derivatives of position. The implication of actively controlled angular velocity lends itself to minimize jerk, combined with reduced power consumption, and an increase in parts life and reliability. This control is applicable to all externally powered prosthetic limbs, regardless of user interface

ELECTROMECHANICAL ANALYSIS OF A COMPLETE ARM PROSTHESIS (EMAS)

A characterisation of a complete arm prosthesis is necessary to develop effective control. This is a description of the use of Lagrange methodology to describe the system and to optimise for motion control. The Lagrange equations of motion are derived from the Newtonian equations of motion. Lagrange analysis describes the system in terms of Kinetic (T) and Potential energies (V). The Kinetic energy (T) is found through a generalised co-ordinate system, where T is a function of the co-ordinates and time derivates. In the non-conservative prosthetic arm, potential energy (V) is found from the generalised forces. These descriptions encompass both electrical and mechanical energies, which are then used to provide the optimum control settings. This analysis method allows multiple terminal analysis points to be combined, allowing an electrical network with losses, and a mechanical network with losses, combined by a coupling network. Thus the analysis allows for n mechanical and electrical terminals in the network. This network approach lends itself to a complete prosthetic arms system, where terminals in the network can range from individual fingers to shoulder joints

Integrated ferroelectric polymer pyroelectric sensors : A comparative study of PVDF and its copolymer VDF/TrFE film

This paper presents a comparative study of integrated pyroelectric sensors based on ferroelectric polymers using different deposition techniques. A 9 µm PVDF film is bonded on a silicon substrate using a capacitive (UV curing acrylic) thin film and a 1 µm VDF/TrFE copolymer is coated directly using a spin-coating technique. The theoretical response of both PVDF and VDF/TrFE pyroelectric sensors are calculated and related to the measured values. Responsivities of 4.3 V/W and 1.2 V/W, at 400 Hz, have been achieved for the pyroelectric sensor based on PVDF and VDF/TrFE copolymer respectively. 1/f noise of the MOSFET is the dominant noise source for both sensors, resulting in an input referred noise voltage of 70 nV/Hz0.5 at 400 Hz

Application of pulsed laser photoacoustic sensors in monitoring oil contamination in water

A pulsed laser photoacoustic measurement technique, utilising laser diode sources, has been developed for the detection of oil contamination in water. The measurement of oil-contaminated water samples of oil concentration ranging from 0 to 900 mg 1−1 is presented. Also reported are results from a theoretical modelling, which includes several experimental factors important to the photoacoustic sensor design for this type of applicatio