A new type of wearable, cloth-based microfluidic device has been developed by scientists in Malaysia inspired by batik-patterned clothes, one of the first studies to show that (bio)chemical assay can also be carried out in non-rigid, flexible materials.
The research on transferring patterned wax on paper to cotton cloth, which was led by Dedy Wicaksono from the Universiti Teknologi Malaysia and published in the journal Lab on a Chip [Nilghaz et al, Lab Chip (2011) doi: 10.1039/c1lc20764d], produced an embeddable microfluidic device for controlling liquid flow in various applications and which is also environmentally friendly.
The textile processing for batik clothing, popular in many Asian countries, uses a wax patterning technique to create regions on the cloth with differing hydrophilicity/hydrophobicity, with the cloth area that has wax on it stopping the dye from spreading between different areas of the cloth, allowing for coloured patterns to be created.
For their approach, the team prepared cotton by cleaning it with sodium hydroxide and anhydrous sodium carbonate solutions, taking off its outer layer so that the underlying cellulose fibers are exposed. With the material now containing more oxygen and having a rougher surface, the wettability and wicking rate were both increased. The pattern for the device was then printed onto paper, dipping it into hot batik wax, before it was dried and the pattern being cut out and attached to the scoured cloth.
Heat treatment is then used to re-melt the wax, which is spread onto the surface and into the cloth, with the gaps in the weave and between the fibers becoming filled. The liquid is prevented from flowing through it due to the fatty acids in the wax raising the hydrophobicity of the fibers on application. This wax patterning on cotton cloth is a cheaper fabrication technique that needs no special equipment or highly trained staff, making the microfluidic devices more flexible and even embeddable into daily clothing.
Although previous research has focused on miniaturizing the lab, to put different analysis in a single chip (the “lab on a chip”), this study puts the lab closer to the sampling site, with the production of channels inside a flexible cloth meaning that an embeddable wearable laboratory where the assay is carried out near or on the sample source could be available in the near future.
The device could offer a rapid and cheap readout for analytes characterised by relatively simple colorimetric assays. The team are now looking at how to have greater control over the liquid flow to allow for more complex microfluidic devices to be developed.
It is hoped the breakthrough will also have direct applications in healthcare, especially for the developing world, with the production of cheap and early diagnostic systems, and in the personal sanitary product industry, such as for diapers or sanitary napkins. The use of liquid flow control in fabrics with nanomaterials or biomaterials is also being investigated.

Laurie Donaldson