Measurement for our planet
Measurement for our planet

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Bajram Zeqiri

Bajram Zeqiri

NPL Fellow

Bajram Zeqiri is an NPL Fellow in Ultrasound and is the Science Area Leader for Ultrasound and Underwater Acoustics and is an internationally-recognised leader in the field of ultrasound metrology, specifically supporting its medical and industrial applications. He has been an NPL Fellow since 2008 and his contributions to the technical field have been underpinned by a passion for innovation, as evidenced by a string of patents related to ultrasound metrology. He works closely with industry, forming strong partnerships with national and international companies and sees this as a mechanism for increasing the speed and depth of impact of NPL's work.


The work of NPL in the ultrasound area has been important in establishing measurement standardisation that underpins the safe and effectiveness of medical ultrasound globally. Bajram's research activities include leading the development of standards for characterising the essential properties of physiotherapy ultrasound equipment; measurement and calibration standards for ultrasonic hydrophones and power measurement, as well as the establishment of reference facilities for determining the acoustic properties of tissue-like materials. One area of particular interest has been the development and characterisation of unique acoustic materials for applications covering the frequency range 10 kHz to 30 MHz, now provided to the user community under Licence.

Bajram has established a track record of innovation related to ultrasound metrology and is the named inventor on six patents. These include the NPL Cavitation Sensor, a device which detects the high-frequency acoustic emissions generated by bubbles undergoing acoustic cavitation. In 2003, a paper describing the Cavitation Sensor won the IEEE Ultrasonics, Ferroelectrics and Frequency Control (UFFC) Outstanding Paper Award and, in 2009, the NPL Cavimeter won the Ultrasonic Industry Association (UIA) Best Product Award for a device using ultrasonic energy. Bajram has also pioneered the application of the pyroelectric effect within thin membranes of the piezo-polymer polyvinylidene fluoride as a robust, solid-state, technique for ultrasound power measurement. A current research topic of interest is the application of these pyroelectric detectors to phase-insensitive Ultrasound Computed Tomography (UCT), supporting quantitative imaging of the attenuation of soft-tissue materials, for potential application in the diagnosis of breast disease.

For over 25 years, Bajram has represented the UK on the key standardisation committee, IEC TC87: Ultrasonics and is a member of Working Groups 6 (Focused transducers), 8 (Ultrasonic field measurement) and Working Group 3 (High Power Transducers), for which he was Convenor. He is a member of BSI Technical Committee EPL/87, the mirror committee of the International Electrotechnical Committee Technical Committee TC87. Other responsibilities of note: contribution to REF2014 as an invited member of Sub-Panel 13B: Electronic and Electrical Engineering, Metallurgy and Materials; Chaired the Strategic Planning Working Group of the CIPM Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV); membership of the UK Institute of Acoustics Research Coordination Committee and the Institute of Sound and Vibration Research (University of Southampton) Advisory Committee; membership of the Institute of Physics in Medicine and Biology (IPEMB) Special Interest Group on Ultrasound and Non-ionising Radiation and twice Convened the EURAMET Sub-committee on Ultrasound and Underwater Acoustics. Through invitation, Bajram contributed to a Working Group formed by the UK Health Protection Agency, whose task was to draft an Advisory Report on the Health Effects of Ultrasound and Infrasound, particularly relating to the public exposure. He was also part of the Technical Programme Committee contributing to the IEEE International Ultrasonics Symposium meeting to be held in Glasgow in October 2019.

From 1 September 2019, Bajram will be Visiting Professor in the University College London Department of Medical Physics and Biomedical Engineering.

Bajram has published 106 articles, 70 of which are peer-reviewed journal articles.

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Selected recent publications

  1. Baker C, Sarno S, Eckersley RJ and Zeqiri, B. Pulse Pileup Correction of Signals from a Pyroelectric Sensor for Phase-Insensitive Ultrasound Computed Tomography (piUCT). IEEE Transactions on Instrumentation and Measurement, PP(99), 1-12, 2018.
  2. Baesso, RM, Costa-Felix, RPB, Miloro, P and Zeqiri, B. Ultrasonic parameter measurement as a means of assessing the quality of biodiesel production, Fuel, 241, 155-163, 2019.
  3. Memoli, G, Baxter, KO, Jones, HG, Mingard, KP and Zeqiri, B. Acoustofluidic measurements on polymer-coated microbubbles: Primary and secondary Bjerknes forces, Micromachines, 9, 8, Article number 404, 2018.
  4. Sarno, D, Hodnett, M, Wang, L and Zeqiri B. An objective comparison of commercially-available cavitation cleaners, Ultrasonics Sonochemistry, 34, 354-364, 2017.   
  5. Fonseca, M, Zeqiri, B, Beard, PC et al. Characterisation of a phantom for multiwavelength quantitative photoacoustic imaging, Physics in Medicine and Biology, 61, 13, 4950-4973, 2016.
  6. Koukoulas, T, Robinson, SP, Rajagopal at al. A comparison between heterodyne and homodyne interferometry to realise the SI unit of acoustic pressure in water. Metrologia, 53, 2, 891-898, 2016.
  7. Ibanez, I, Hodnett, M, Zeqiri, B and Frota, M. Correlating inertial acoustic cavitation emissions with material erosion resistance, 44th Annual Symposium of the Ultrasonic Industry Association, Book Series: Physics Procedia, 87, 16-23, 2016.
  8. Rajagopal, S, Fury, C and Zeqiri, B at al. Report on BIPM/CIPM Key Comparison CCAUV.U-K4: Absolute calibration of Medical Hydrophones in the frequency range 0.5 MHz to 20 MHz Final Report. Metrologia, 53S, Article Number 09004, 2016.
  9. Fonseca, M, Saratoon, T, Zeqiri, B, Beard P and Cox, B. Sensitivity of quantitative photoacoustic tomography in version schemes to experimental uncertainty. Photons plus ultrasound imaging and sensing. Book series: Proceedings of SPIE meeting, San Francisco, California, Volume 9708, Article number: 97084X, 2016.
  10. Wang, L, Memoli, G, Hodnett, M, Butterworth, I, Sarno, D and Zeqiri, B.  Towards a reference cavitating vessel Part III – Design and acoustic pressure characterisation of a multi-frequency sonoreactor. Metrologia, 52, 4, 575-594, 2015.
  11. Zeqiri, B, Cook, A, Retat, L, Civale, L and ter Haar, G. On measurement of the acoustic nonlinearity parameter using the finite amplitude insertion substitution (FAIS) technique. Metrologia, 52, 2, 406-422, 2015.
  12. Bornmann, P, Hemsel, T, Sextro, W, Memoli, G, Hodnett, M and Zeqiri, B.  Cavitation detection by a self-sensing ultrasound transducer. TM-Tecsniches Messen, 82, 2, 73-84, 2015.
  13. Wang, L, Memoli, G, Hodnett, M and Zeqiri, B. Dynamic behaviour of laser nucleated bubbles in a focussed ultrasound field. 2015 IEEE International Ultrasonics Symposium (IUS) Book Series, 1-4, 2015.
  14. Fonseca, M, Zeqiri, B, Beard, P and Cox, B. Characterisation of a PVCP based tissue-mimicking phantom for quantitative photoacoustic imaging. Opto-acoustic methods and applications in biophotonics II Book series: Proceedings of SPIE, Volume 9539, Article number: 953911, 2015.
  15. Rajagopal, S, Sadhoo, N and Zeqiri, B. Reference characterisation of sound speed and attenuation of the IEC agar-based tissue-mimicking material up to a frequency of 60 MHz, Ultrasound in Medicine and Biology, 41, 1, 317-333, 2015.
  16. Kenwright, DA, Sadhoo, N, Rajagopal, S and Zeqiri, B. Acoustic assessment of a konjac-carrageenan tissue-mimicking material at 5 - 60 MHz. Ultrasound in Medicine and Biology, 40, 12, 2895-2902, 2014.
  17. Rajagopal, S, Zeqiri, B and Gelat, PN. Calibration of miniature medical ultrasonic hydrophones for frequencies in the range 100 to 500 kHz using an ultrasonically absorbing waveguide. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 61, 5, 765-778, 2014.
  18. Bornmann, P, Hemsel, T, Sextro, W, Memoli, G, Hodnett, M and Zeqiri, B. Self-sensing ultrasound transducer for cavitation detection. IEEE International Ultrasonics Symposium (IUS) Book Series, 663-666, 2014.
  19. Koukoulas, T, Rajagopal, S, Robinson, SP, Moss, B, Zeqiri, B and Theobald, PD. Primary ultrasonic interferometer photodiode characterisation using frequency modulated laser wavefront radiation. Metrologia, 50, 6, 572-579, 2013.  
  20. Zeqiri, B, Baker, C, Alosa, G, Wells, PNT and Hai-Dong Liang. Quantitative ultrasonic computed tomography using phase-sensitive pyroelectric detectors. Physics in Medicine and Biology, 58, 15, 5237- 5268, 2013.