Contact Transfer of Liquids Between Impermeable Rigid Surfaces in Close Contact

Exposure modelling can provide vital information informing quantitative risk assessments in a range of scenarios involving biological and chemical hazards, e.g. as was used during the COVID-19 pandemic [1]. Contact transfer is one of the key exposure pathways and must therefore be quantitatively understood for a wide range of hazards and substrates to estimate exposure of and redistribution of contamination by humans interacting with the contaminated environment.

We present an investigation into the contact transfer of liquids between impermeable, rigid surfaces brought into close contact as a function of physical parameters, in particular viscosity and contact angle. Droplets of fluorescein-dyed liquid are placed onto a smooth surface, which is then brought into close contact with a smooth contact sampler. After separation, both surfaces are extracted and the transferred amount of liquid determined from the amount of fluorescein found on each surface.

The results are analysed as a capillary bridge problem [3] and compared against previous results obtained for a sebum-coated artificial finger [2].

 [1] - Miller, Daniel, et al. "Modelling the factors that influence exposure to SARS‐CoV‐2 on a subway train carriage." Indoor Air 32.2 (2022): e12976.

[2] - Walker, M. D, et al. “Effect of Relative Humidity on Transfer of Aerosol-Deposited Artificial and Human Saliva from Surfaces to Artificial Finger-Pads”, Viruses, Multidisciplinary Digital Publishing Institute (2022), 14, 1048.

[3] - Chen, H., et al. "Fast liquid transfer between surfaces: breakup of stretched liquid bridges." Langmuir 31.42 (2015): 11470-11476.