The Advantages of Stretchable Inks in Heaters

Electric vehicles are increasingly popular and space flights are commercialized, yet consumers are still sitting close to an outlet with an uncomfortable wired heater to keep warm. Portable heating serves many industries, including medical, apparel, automotive, and more, but traditional wired heaters are bulky and inflexible. Printed heaters, made with conductive silver stretchable inks, are flexible without sacrificing heat.

Heaters made with stretchable inks are soft, compliant, conforming, battery-powered, and washable, eliminating uncomfortable wires and bulky cords. ACI Materials offers all the necessary materials to build a new generation of stretchable heaters.

How Flexible Printed Heaters are Built

Flexible heaters are made through a precision printing process using silver and carbon conductive, stretchable inks. The ink adheres to a stretchable thermoplastic polyurethane (TPU) base layer. After drying, the ink has excellent conductivity, elongation, and flexibility.

The stack includes a stretchable printed silver conductor used to create the busbar system. The busbar system allows electricity to flow through the device.

Printed fixed-resistance heater ink is then used to create a resistive layer. The next layer uses a stretchable encapsulant as an insulator, which can be customized with different graphics or logos.

The completed circuit on TPU is then integrated onto various fabrics and then attached to a battery pack for power.

The Advances in Stretchable Inks

Stretchable ink technology has come a long way in the past several years. Stretchable inks are now the ideal solution for printed electronic devices like flexible heaters.

• Easy to apply

The ACI cavitation process advantage ensures uniform heat and batch-to-batch consistency.

• Better performance

ACI’s superior cavitation process eliminates the initiation sites that can cause failure at lower stress levels. This leads to a more robust performance of conductive inks as the stresses associated with thermal expansion and mechanical deformation are less likely to cause cracking, delamination, or line breaks. Stretchable inks can elongate to greater than 200 percent without cracking. Improved dispersion also improves fatigue of these materials, especially for stretchable products, as the solid phase moves more easily and predictably within the polymer matrix. This mitigates the onset of damage within the material as the ink is cycled during use. The stretchable inks also offer resistivity and rapid return after strain.

Compared to other materials used for wearable heaters like conductive threads, stretchable inks are far superior because of their comfortability. Conductive threads, although smaller than wires, are not as soft as cotton threads and end up feeling like small wires.

The Advantages of Heaters Made with Stretchable Inks

Because of their durability and stretchability, heaters made with conductive inks offer several advantages over traditional wired heaters or ones made with conductive threads, including:

1. Comfortable

Printed heaters are made with very thin layers of stretchable inks, making them almost incognito in apparel or other uses. They are soft to the touch and can conform to the body when applied to clothing. The thin inks provide less bulk than traditional wires, making them easy for transport in outdoor scenarios like sleeping bags.

2. Battery-Powered

Printed heaters do not need cords and an outlet, batteries power them. Depending on the use, the size of the battery pack can vary, but they can be as small as a coin cell battery. Battery power makes these heaters ideal for on-the-go situations such as camping, hiking, running, skiing, and more.

3. Washable

Battery packs can be removed from the heater so the fabric can be washed. The heater can be machine-washed and last through multiple cycles. Handwashing is recommended for high-use scenarios.

Contact ACI to Get Started

ACI Materials collaborates with clients and various functional printers to create the perfect heater for multiple applications. Contact us to learn more about stretchable inks and get started on your next flexible heater project.