Apart from screens on mobile phones, every other electronics device is getting smaller, enabling new applications, writes Caroline Hayes.

Increased portability is creating new applications, wearable devices, circuitry used in ever-diminishing spaces and some fascinating developments in flexible circuits.

Flexible circuitry evolved from being simply wire placement to the development of complex circuits with improved power consumption and faster clock speeds that can perform in contoured placements in mission‑critical aeronautical and automotive systems as well as consumer, telecom, healthcare and industrial applications. Its fascination lies in the fact it enables electronic designs to be curved and angled as well as small and portable.

The market is expected to achieve 11% CAGR between 2018 and 2026 (source: Maximize Market Research), as it is deployed in automotive and healthcare systems, OLEDs and LCDs.

In healthcare, it is used for consumer devices, to monitor and track a patient’s heart rate or blood pressure without a visit to the hospital or doctor’s surgery. As polymers and substrates improve in terms of flexibility and resistance to moisture, they are increasingly used in sporting applications, to track and monitor a swimmer’s style or a runner’s gait, heart rate and other physical parameters.

Du Pont has played in this market for decades, with products like Pyralux AG, a polymide, double-sided, copper-clad laminate, offered in sheets and rolls. It is stable and with low losses it is used in sensors, speakers and cameras for smartphones, but is expected to transition to medical and automotive uses too.

Consumer, healthcare and automotive markets are also using flexible batteries. This is another area which is expected to experience significant growth, increasing from $85.6m in 2017 to $1142.6m by 2026 (source: Maximize Market Research). This represents a CAGR of 38.25%.

Here, packaging is the key to design creativity, as disposable batteries, sensors and circuits are integrated into tags and labels to provide information about the product, conditions or location.

PragmatIC makes ConnectIC RFID FlexICs in the UK and has been working with partners to produce custom circuits with companies like Arm (to design a machine learning chip on a flexible substrate that recognises odours).

The flexible, lightweight circuits can be used on curved items, like bottles, to make sure your beer is always served at the right temperature, for instance, or to let you know when there is a special offer in case you need to top up supplies. Equally, it can be used to add intelligence or connectivity to toys and games to encourage learning or to engage children with special needs to draw their attention to particular areas.

As well as materials and conductive inks to create the substrates, a graphene‑oxide circuit was screen‑printed onto fabric at the University of Manchester. The team reported that the result was washable, meaning that truly a wearable electronic garment is another step closer.

Fashion-technology company, CuteCircuits flirted with the concept of wearable circuitry as long ago as 2002, when it showed its Hug Shirt during New York Fashion Week. The garment, with integrated sensors and actuators, connects to a smartphone app, to ‘send hugs’ to someone else wearing a Hug Shirt who will feel the hug through matching sensors placed on their own shirt. If they are not wearing the Hug Shirt, the loving gesture can be sent to the recipient’s smartphone instead (just don’t get your contacts list get muddled!). The shirt is rechargeable and washable.

When circuits can be printed or inlaid and can stretch with the fabric’s fibres – and then withstand washing – the creativity of design engineers and fashion and interior designers is likely to be further unleashed.