Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

Effect of Material and Geometry on SurFlow™

Project Code: 33567


  • Achieve a reliable, qualitative method of assessing SurFlow™, through the development of a test bench.
  • Understand the effect of material on SurFlow™ by changing the fibre type, weave type, stacking sequence and the matrix of the composite, and measuring the signal propagation in simple laminates.
  • Understand the effect of geometry on SurFlow™ by introducing a variety of geometrical features to composite structures and measuring the signal propagation.
  • Understand the effect of transducer design on SurFlow™ by varying transducer design, performing electromagnetic (EM) simulation, and measuring signal propagation.
  • Establish SurFlow™ reliability by measuring data propagation speed, signal leakage and electromagnetic interference (EMI).

Project Outline

SurFlow™ technology allows signal propagation from one end to the other of a composite surface without the use of wiring harnesses or fibre optics. The signal travels over the composite surface in the form of an electromagnetic surface wave (EMSW). The signal is bound to the composite structure. There are three requirements for an EMSW to function:The following challenges related to SurFlow™ will be investigated in this project:

  • The wave must be launched with the correct incident angle.
  • A medium compatible with EMSW propagation.
  • The waveform must be acquired and translated at the receiving end.


Although demonstrations have been performed on different composites (glass, carbon etc) it has not been quantitatively established how the material affects the signal propagation. That means the effect of fibre type, weave type, stacking sequence, resin type etc are yet to be quantified.


The effect of geometric features such as joints and curvatures is not fully understood. Depending on the location of the interface in which the signal propagates and the location of the feature (joint, curve) in the structure, the effect on the signal could be different.


The transducers developed for SurFlow™ have not been characterised in an anechoic chamber. Although the aim was to optimise the transducer for EMSW propagation, they also emit an electromagnetic airwave (EMAW). The intensity of the EMAW increases when higher power levels are used to launch the wave. The transducer design, signal power level and control, and transducer shielding will be investigated in order to tailor the EMSW to EMAW ratio. Furthermore, the effect of EMI has not been assessed. This work will be carried out in an anechoic chamber.


Off-the-shelf electronics have been used for transmitting and receiving the EMSW signals. However, these are not optimised for SurFlow™. Quantitative data measurements of the coefficient of signal transmission have been carried out using a vector network analyser. This work now needs to be repeated in an anechoic chamber.

Test reliability and repeatability

The test set-up for testing SurFlow™ is laboratory-based and currently has not been standardised. In order to compare different materials, structures and frequencies, the test set-up has to be standardised, in the form of a test bench, for repeatability and reliability.

Relevant Industry Sectors

Benefits to Industry

Industry can use the SurFlow™ test bench to assess whether composite structures are compatible with SurFlow™. Findings will provide industry with improved understanding of the technology and an indication of the reliability of SurFlow™ for specific applications.


 Research Board Portal

For more information please email: