Mapping the road between digital twins and NDE

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RoadmapMichael Grieves, who probably first formulated the concept of digital twins in 2002, stated that all information about a physical entity should be present in its cyber or digital twin with data flow from the physical entity to the digital twin, and information flow from the digital twin to the physical entity throughout its lifecycle [1] [see ‘Digital twins that thrive in the real-world’ on June 9th, 2021].  The realisation of data flows between cyber-physical twins has been slow and there are relatively few cases where this definition has been fully implemented.  Non-destructive evaluation (NDE) is a well-established set of techniques used to assess the properties, integrity and condition of engineering components and structures that could play a significant role in supplying data to digital twins.  At the moment NDE is commonly used in quality control to check for manufacturing defects, in integrity assessments to investigate damage in safety critical components during maintenance inspections, and for determining the remaining life expectancy of engineering parts.  The integration of NDE in digital engineering has been slow; so, in a recent study, involving representatives from a wide range of industries, we have defined in a roadmap [2] the potential opportunity and the route to its realisation.  This work represents a different approach to research for my group in that we have explored the need or the ‘pull’ from industry rather than delivering innovative technology which can result in a ‘push’ to industry [see for example, ‘Our last DIMES’ on September 22nd, 2021].  My regular readers might also detect the influence of social science, which also surfaced in our recent work on knowledge management [see ‘Opportunities lost in knowledge management using digital technology’ on October 25th, 2023 and ‘Evolutionary model of knowledge management’ on March 6th 2024].  We have used the same methods, based on semi-structured interviews and thematic analysis, across all of these studies.

Image: roadmap [© University of Liverpool] which should be read in conjunction with [2].

References:

  1. Grieves, M., Vickers, J. (2017). Digital Twin: Mitigating Unpredictable, Undesirable Emergent Behavior in Complex Systems. In: Kahlen, J., Flumerfelt, S., Alves, A. (eds) Transdisciplinary Perspectives on Complex Systems. Springer, Cham.
  2. Middleton CA, Nguyen T & Patterson EA, NDE4.0 and digital twins in industry: current user experiences and future development, J. Nondestructive Evaluation, 45:107, 2026.

Iron Nanochains

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Caustics formed from iron nanoparticles coalescing into chains aligned with the lines of the magnetic field from an adjacent magnet

Many people will be familiar with an iron filings and magnet experiment often performed in high school physics classes.  Iron filings on a sheet of paper with a magnet underneath, when the paper is gently tapped, align with the lines of the magnetic field sometimes forming ‘chains’.  In our research group, we have performed a version of this experiment at the nanoscale using iron nanoparticles smaller than 200nm in diameter floating in deionised water on a microscope slide.  We brought a magnet into close proximity with the slide and the nanoparticles formed chains aligned along the lines of magnetic field which we visualised using caustics [see ‘Holes in fluids’ on October 22, 2014].  When we removed the magnet, the nanoparticles resumed their Brownian motion.  Not a ground-breaking experiment but it’s exciting to be able to demonstrate that the phenomenon occurs at the nanoscale and that we can observe it.

Worldly goods and routes to happiness

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Decorative image of a flowerIn her novel, ‘The Gap of Time’, Jeanette Winterson writes that Buddha and Jesus knew that when you had so much money that you could buy anything, everything, then worldly goods were worthless.  Modern capitalism has generated a small number of owners of capital who have this much money.  For the rest of us worldly goods are not valueless or worthless.  Omnipresent advertising tends to create a desire in many of us for a lifestyle that is unattainable with our income, which can lead us to be dissatisfied and unhappy.  Some surveys have suggested that engineers are amongst the happiest people [see ‘Choosing a career is like going shopping’ on June 17th, 2015].  Perhaps this is because we managed to do as Rutger Berger suggested in his 2025 BBC Reith Lecture, which is to measure our success in terms of our contribution to tackling humanity’s toughest problems.  For many engineers, this is a key component of their role.

Sources

Jeanette Winterson, The Gap of Time, Penguin, London 2015

Simon van Teutem, How our brightest minds get trapped in the city, FT 18/19 October 2025.

Real-time label-free tracking of bacteriophages interacting with bacteria

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(a) Two-dimensional random dynamics (blue line) of a pelp20 bacteriophage monitored for a period of 5 s. Scale bar, 2 µm. (b) A plot of the same dynamics and (c) the mean square displacement (MSD) of the random walk. The MSD of the random walk is represented by square data points, and a linear fit (black line) has been applied to the data.

(a) Two-dimensional random dynamics (blue line) of a pelp20 bacteriophage monitored for a period of 5 s. Scale bar, 2 µm. (b) A plot of the same dynamics and (c) the mean square displacement (MSD) of the random walk. The MSD of the random walk is represented by square data points, and a linear fit (black line) has been applied to the data (Figure 4 from https://royalsocietypublishing.org/view-large/figure/20098614/rsif.2026.0250.f004.tif)

I was excited last month when our latest research on tracking nano-entities was published by the Journal of the Royal Society Interface.  The paper describes the real-time and label-free tracking of bacteriophages, or phages, in an optical microscope using caustics (see right thumbnail).  Phages are of interest due to the potential applications in biotechnology and medicine.  They selectively infect and replicate within bacteria and play an important role in regulating bacterial populations across many ecosystems.  I have written previously about the threat of antimicrobial resistant (AMR) infections and our research on the real-time tracking of individual bacterium that could be responsible for such infections [see ‘Label-free real-time tracking of individual bacterium‘ on January 25th, 2023].  In this newly published paper, we describe tracking phages as they interact with and compromise bacteria (see bottom thumbnail) using the same technique, optical caustics [see ‘Caustics‘ on October 15th, 2024 and application to ‘Nanoparticle motion through heterogeneous hydrogels‘ on November 6th, 2024 and to ‘Corona-induced transition from molecular to particle motion in biological media‘ on December 4th, 2024]. Traditionally, phages have been monitored using fluorescent labelling because their size is nanometric which renders them invisible in a conventional optical microscope.  However, chemically attaching labels to nano entities has been shown to influence their dynamics.  Hence, this new study represents a significant advance that will accelerate the real-time observation of phage-bacteria interactions which will enable the development of phage-based diagnostics and antimicrobial therapies.

Sources:

Francesco Giorgi, Samuel Chenery, Liberty Duignan, Joanne L. Fothergill, Eann Patterson, Judith M. Curran; Elucidating bacteriophage dynamics and interactions with real-time label-free optical imaging. J R Soc Interface 1 May 2026; 23 (238): 20260250. https://doi.org/10.1098/rsif.2026.0250

Details of E. coli bacteria: (a) not exposed (reprinted from [17]) and (b,c) exposed to a population of EcoLiv25 phages in solution. In (b), the arrow points at the supposed presence of a phage attached to the bacterium’s external membrane, while in (c), the arrows point at the compromised sections of the bacterium’s external membrane as a result of phage infection. Scale bars, 2 µm.

Details of E. coli bacteria: (a) not exposed and (b,c) exposed to a population of EcoLiv25 phages in solution. In (b), the arrow points at the supposed presence of a phage attached to the bacterium’s external membrane, while in (c), the arrows point at the compromised sections of the bacterium’s external membrane as a result of phage infection. Scale bars, 2 µm (Figure 6 from https://royalsocietypublishing.org/view-large/figure/20098622/rsif.2026.0250.f006.tif).