skip to content

Cambridge Global Food Security

An Interdisciplinary Research Centre at the University of Cambridge


Charlie is a final year PhD student funded by the EPSRC. His PhD is a collaboration between the Nanomanufacturing group at the Institute for Manufacturing and the Bio-inspired Photonics group at the Department of Chemistry, both of the University of Cambridge.


Charlie's work is focused around a cellulose-derivative, Hydroxypropyl Cellulose (HPC), which upon dissolution self-assembles into a lyotropic liquid crystalline mesophase. Under certain conditions of concentration, temperature and pressure, HPC gives rise to vibrant, iridescent structural-colours. A “structural colour” is a photonic effect that provides a stable colour over time as the colour as it is not the result of any pigments or dyes. Therefore, the colours do not fade due to usual processes like UV exposure. Furthermore, as light is reflected by following the Bragg-condition the final observed colour can be tuned in various ways, for example, by applying pressure or changing the concentration.

HPC has proven bio-compatibility in the food and pharmaceutical industries as a bulking, binding and drug release agent in pills, as a gluten-substitute in foods and even as an eye-treatment. It is edible, bio-degradable, low-cost and already produced in large quantities world-wide. It is also easily derived from cellulose, the most abundant natural polymer in the world. These points combine to make HPC highly suited for industrial scaling in a sustainable and environmentally friendly manner, if only more photonic applications were realised.

To this end, Charlie has recently trapped the vibrantly coloured HPC phase into the gel state so that it can be used as a novel food aesthetic, while still retaining it’s dynamic colour changing properties for use in biocompatible sensing applications. For example, it could be used to produce vibrant and iridescent sweets, jellies and/or food/cake decorations that change colour as you move around or touch them. Or it could be used to increase the spatial resolution of mechanochromic sensors without the use fo external architecture. The pressure and humidity sensitivity also has applications as in biocompatible sensors, for example, biodegradable food packaging. 

Neatr the end of this PhD, Charlie is now working to study the pressure-colour (termed, “mechanochromic") response of HPC at decreasing length scales to better understand its application as a cheap, biodegradable display technology.