Sensors and Instrumentation

The group’s work focuses on sensor networks and ultrasonic systems.

Ultrasound has a clear and growing role in modern medicine and there is increasing demand for the introduction of ultrasound contrast agents such as microbubbles.  So-called ‘third generation’ microbubbles will not only allow functional imaging with greatly enhanced sensitivity and specificity but will also carry therapeutic payloads for treatment or gene therapy.  These can be released by destroying the microbubbles at the targeted site and their effect enhanced further by sonoporation, which is the subject of a recent EPSRC-funded project in collaboration with the School of Physics and the Leeds Institute of Molecular Medicine.

A further leading area of ultrasound research is signal coding and pulse compression techniques.  We have demonstrated, in collaboration with BP, a novel switched excitation method, which is digitally controlled and enables complex coded excitation signals to be generated on multiple channels without analogue means.

In collaboration with Leeds Dental Institute, we are investigating the diagnostic applications of ultrasound in dentistry and the use of long-duration linear frequency modulated chirp excitation.  A fractional Fourier technique is applied to tooth imaging by analyzing and filtering chirp signals, overlapping in both the time and frequency domains, where the common time or frequency based filtering is not applicable.  The intended application of the proposed technique is producing an image of tooth enamel and underlying dentino-enamel junction.

Finally, we are developing new harmonic imaging techniques that rely on nonlinear propagation of the sound waves into the medium (tissue or contrast agents), which gradually deforms the wave shape. This work exploits signal-processing techniques to encode the excitation waveform and requires only single transmission that helps to avoid frame rate reduction and movement artifact problems.

In the area of sensor networks, we are using our expertise in communications and navigation at all layers of the OSI model to contribute to the rapidly developing area of wireless sensor networks (WSN).  Predominantly WSN applications rely on knowledge of location, and GPS positioning is not suitable for WSNs.  So, localization is provided through implementation of ranging between nodes and algorithms to determine position from this range information.  An earlier Leeds project, iPLOT, developed this technique for Bluetooth-based networks and current work is extending this to other networks such as Zigbee.  This work is also being extended through use of geographically based routing algorithms in sensor network.  Many different aspects of this area are being investigated such as the location resolution achievable with currently available WSN hardware (and methods to enhance this).  Other aspects being investigated include using the localization of nodes to form the basis of routing algorithms, investigation of cross-layer optimizations.

Academic staff
Dr S Freear
Dr A Kemp