REVEALing complex strain patterns and dangerous loads using cholesteric liquid crystal elastomers

The Internet of Things (IoT), Industry 4.0, and the increased availability and performance of sensors have led to new generations of ‘smart’ products that can communicate real-time status information, improving energy balance, increasing safety, and opening for better, more seamless experiences for consumers.

Mechanical sensors—often measuring strain—are key components in many scenarios.

However, current technology typically employs point-based or one-dimensional (1D) strain sensors of resistive, piezoelectric or optical fiber type, with low spatial resolution (one sensor, one value), giving limited information about complex deformations and even missing dangerous strains slightly away from the sensor.

There is thus a need for new solutions that offer 2D distributed strain sensing with high resolution.

We recently proposed two new concepts for non-electronic strain sensing, both based on the mechanochromic response of Cholesteric Liquid Crystal Elastomers (CLCEs), changing colour in response to mechanical deformation.

The value proposition of REVEAL comprises simple and scalable procedures for making CLCE sheets of large size and fibers of arbitrary length, which exhibit excellent local mechanochromic response (from red to violet) upon strains of up to 200%.Within REVEAL, we will produce CLCE sheets and fibers and assess their application potential, for instance, in structural health monitoring of the built environment, smart clothing and sports gear.

The challenges we wish to take on in REVEAL are: ensuring consistent and tuneable relaxed colour with sufficient time stability of our CLCE sheets and fibers; allowing adjustable and well-defined diameter of the CLCE fibers; reducing tackiness of the fibers, thus enabling easy manipulation and processability at large scale; ensuring strong full-area bonding to each relevant target surface of the CLCE sheets; and assessing the usefulness in four specific target applications, two for each CLCE type.