Researchers at Penn State have developed an unexpectedly accessible, low-cost method for producing wireless, shape-conforming electronic devices — a breakthrough with potential for designers working in wearables, consumer products, interiors and smart packaging. By printing liquid-metal circuits onto heat-shrinkable polymer sheets, the team has created electronics that can adapt to complex 3D surfaces, from the human body to everyday objects.

The approach, published in Science Advances, uses the familiar children’s craft material Shrinky Dinks as a functional substrate. When heated, the plastic sheet shrinks uniformly, allowing a printed circuit to miniaturise and wrap itself around curved geometries. This opens the door to customisable, IoT-enabled components that can be produced at low cost and without specialist equipment — a significant advantage for designers aiming to explore smart or responsive materials.

Liquid Metal as a Functional Conductor

Traditional circuit metals such as gold or silver are rigid and incompatible with the shrinking process. Instead, the team used a gallium-indium liquid metal alloy, modifying it through ultrasonication and a detergent-like additive to create stable droplets that remain conductive and adhere strongly to the polymer. A plasma treatment further enhances bonding, enabling the circuitry to withstand thermal shrinking while retaining electrical performance.

The resulting material system forms a hybrid structure where liquid metal fills microscopic pores in the polymer, creating a mechanically robust and reliable conductive network. Tests showed a 20% increase in adhesion, supporting long-term functionality — essential for wearables and embedded sensors.

From Wearable Rings to Smart Household Objects

As a proof of concept, the researchers produced a wearable ring containing a miniaturised accelerometer capable of transmitting gesture data over a wireless network. Because the process supports precise control of material shrinkage, the team could also shape antennas directly onto 3D surfaces. This could allow designers to retrofit existing objects — furniture, devices, packaging — with intelligent capabilities without the need for bespoke hardware.

For fashion and product designers, the technique presents a pathway to low-profile, flexible electronics integrated into garments or accessories. For interior and packaging designers, shrink-formed antennas and sensor modules could provide new tools for smart environments, track-and-trace systems or responsive surfaces.

Accessible Fabrication for Designers

One of the most promising aspects of the method is its accessibility: shrink-plastic sheets can be purchased inexpensively, and the printing process relies on scalable techniques rather than specialised fabrication facilities. This positions the technology as a potential DIY platform for early-stage prototyping of smart materials and interactive products — lowering the barrier for experimentation in connected design.

Penn State’s team is now exploring improved antenna architectures and biomedical applications, highlighting a future where custom, body-conforming sensors could offer personalised health monitoring across diverse body shapes and conditions.

Source: Penn State University
Photo: Courtney Robinson