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Colour-changing inks can be printed on clothing to warn the wearer of potential health problems.

Thanks to a recent development at Tufts University School of Engineering, we may soon be able to wear clothing that can change colour in response to chemicals released from our bodies or detected in the air.

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Bioactive inks in the service of health.

Biomaterial-based inks can be screen-printed on textiles such as clothing, footwear or even face masks in complex, high-resolution patterns, providing a detailed map of human response or exposure.

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Advances in clothing detection could allow a wide range of biological factors, molecules and possibly pathogens to be simultaneously detected and quantified on the body surface using conventional clothing.

Fabrics suitable for clothing.

The use of new bioactive inks with the very common method of screen printing opens up promising prospects for the mass production of soft, portable fabrics with a large number of sensors that could be applied to detect a wide range of conditions,” said Professor Fiorenzo Omenetto, author of the study.

Fabrics can be found in workplace uniforms, sportswear, or even on furniture and architectural structures”. Clothing detection devices have generated considerable interest in monitoring human performance and health. Many of these devices have been invented by integrating electronics into patches, wristbands and other portable configurations that monitor localized or global physiological information such as heart rate or blood glucose levels.

Silk as the base of the ink.

The research presented by the Tufts team takes a different and complementary approach: non-electronic colorimetric detection of a theoretically very large number of substances using detection garments that can be distributed to cover very large areas: from a patch to the whole body and beyond.
The research presented by the Tufts team takes a different and complementary approach: non-electronic colorimetric detection of a theoretically very large number of substances using detection garments that can be distributed to cover very large areas: from a patch to the whole body and beyond.

The components that make sensor clothing possible are biologically activated silk-based inks. The soluble silk substrate in these ink formulations can be modified by incorporating various “indicator” molecules, such as pH-sensitive indicators or enzymes such as lactate oxidase to indicate lactate levels in sweat. The former could be an indicator of skin health or dehydration, while the latter could indicate levels of wearer fatigue.

Organic and screen-printable inks.

Many other ink derivatives can be created from the versatility of silk protein by modifying it with active molecules such as chemically sensitive dyes, enzymes, antibodies and others. Although the dye molecules may be unstable on their own, they can become stable when incorporated into the silk fibroin in the ink formulation.

The inks are formulated for screen printing applications by combining them with a thickener (sodium alginate) and a plasticizer (glycerol). Screen-printable bio inks can be used like any ink developed for screen printing, and can therefore be applied not only to clothing but also to various surfaces such as wood, plastic and paper to generate patterns ranging from hundreds of microns to tens of meters.

There are many possible uses for this product.

This technology builds on previous work by the same researchers who developed bioactive silk inks formulated for inkjet printing to create petri dishes, paper sensors and laboratory gloves that can indicate bacterial contamination by changing colour.

The screen printing approach offers the equivalent of a large multiple array of sensors covering large areas of the body, if worn as a garment, or even over large areas such as the inside of a room,” said Giusy Matzeu, an assistant research professor in biomedical engineering at the school and first author of the paper. “Coupled with image analysis, we can obtain a high-resolution map of colour reactions over a large area and get a better picture of the overall physiological or environmental condition. In theory, we could extend this method to monitor air quality, or support environmental monitoring for epidemiology”.

Interactive exhibits allow you to test these new fabrics.

The fact that the method uses common printing techniques also opens up possibilities for creative applications, which was explored by Laia Mogas-Soldevila, architect and recent doctoral student at Tufts in the Omenetto SilkLab. She has contributed to the creation of magnificent tapestries, which are exhibited in museums throughout the United States and Europe.

The exhibits are interactive, allowing visitors to spray different non-toxic chemicals on the fabric and observe the transformation of the patterns. “This is really a great example of how art and engineering can enrich and inspire each other,” said the architect. “Technical inks open up a new dimension in tapestries and interactive and reactive surfaces, while the age-old art of screen printing has provided a well-suited basis for the need for a modern, high-resolution and portable sensitive surface”.

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