Page 32 - ILLS Annual Report 2018

SOFT MATTER
Marco Adamo. Italian
Imperial College, London
‘While SANS is a unique probe for studying soft matter and complex fluids, microfluidics is a powerful tool for sequentially preparing formulations. My work focuses on the coupling of microfluidics and SANS for the study of soft matter.’
Droplet microfluidic SANS
Small-angle scattering diffractometer D22
The coupling of microfluidics and small-angle neutron scattering (SANS), made possible by judicious choice of microfabrication techniques and materials, enables a range of new experiments on soft matter. Microfluidic chips can be
used as formulators to precisely scan
an unprecedented parameter space of
a phase diagram by tuning the relative flow rates of the inputs. By adding an immiscible fluid, it is possible to generate segmented flows that minimise axial dispersion and ‘cross-talk’ between
fluid compositions. Using D22, we investigated an aqueous suspension of silica nanoparticles by contrast variation and serial dilution, paving the way for phase mapping in microfluidic-SANS and global, constrained, data-fitting.
AUTHORS
M. Adamo, A.S. Poulos, C.G. Lopez and J.T. Cabral (Imperial College, London, UK)
A. Martel and L. Porcar (ILL)
ARTICLE FROM
Soft Matter 14 (2018) 1759—doi: 10.1039/C7SM02433A
REFERENCES
[1] C.G. Lopez et al., Sci. Rep. 5 (2015) 7727
[2] M. Adamo et al., Lab. Chip. 17 (2017) 1559
[3] C.G. Lopez et al., J. Appl. Crystallogr. 51.3 (2018) 570
Microfluidics has been demonstrated to be compatible with SANS, in particular in the processing of complex fluids [1]. Furthermore, new approaches for data correction and calibration have been proposed to take into account beam over-illumination [2, 3]. This study employs microfluidics to prepare liquid samples, in
order to resolve a SANS bottleneck without resorting
to automated, liquid-handling robots, and enabling adaptive, responsive protocols for composition scanning. Typically, experimental approaches require the user to prepare five to ten solutions, pipette them into quartz cells, perform the experiment and then start again. While robotics requires a large capital investment (and
is arguably less flexible), microfluidics enables liquid samples to be rapidly prepared from stock solutions at
a relatively low cost compared with other techniques. Furthermore, it is possible to adjust the resolution of the scan in order to adapt the experiment to the properties of the scatterer: for highly scattering systems (concentrated surfactant solutions, nanoparticle suspensions), data acquisition times can be reduced to a few seconds, enabling the scanning of 100s−1000s compositions; whilst for weakly scattering systems (e.g. dilute polymer or protein solutions) the resolution can be reduced
Figure 1
Schematic of the microfluidic-SANS set-up.
ANNUAL REPORT 2018