Flexible e-QR Codes | The Future of Printed Electronics

Discover how microfabrication on flexible substrates enables dynamic electronic QR codes, bridging printed electronics with real-time sensing.

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Published September 22, 2025 By EngiSphere Research Editors

In Brief

Researchers microfabricated a flexible electronic QR code display using printed electronics on Kapton, enabling low-cost, real-time sensor data sharing via smartphone scans.

In Depth

From Paper to Pixels: Why Electronic QR Codes?

When you scan a QR code on a poster, a menu, or even a bus stop ad, you’re looking at a static block of black-and-white squares. But what if those little squares weren’t just printed ink… what if they were electronic and capable of changing in real time?

That’s exactly what researchers from the University of Pretoria have achieved: the microfabrication of an electronic QR (e-QR) code on a flexible substrate. Their work shows how printed electronics can power real-time sensor data displays, offering a low-cost and energy-efficient alternative to traditional sensor networks.

Instead of cloud-heavy, hardware-intensive IoT setups, this approach allows you to simply scan a dynamic e-QR code with your phone to instantly see updated sensor readings—whether it’s air quality, temperature, or other environmental data.

The Big Idea: Microfabrication Meets QR Tech

Traditional sensors often rely on costly wireless communication systems that push data to the cloud. That’s powerful but comes with downsides: high energy use, complex hardware, and ongoing costs.

The team’s alternative? Use microfabrication and printed electronics to build a dynamic QR code directly on a flexible film.

  • Each LED = one pixel of the QR code.
  • A 21 Ă— 21 matrix = 441 pixels total, the standard size for a Version 1 QR code.
  • These LEDs light up in patterns that encode data, creating a scannable code that updates as sensors feed new values.

In short: the QR code itself becomes the screen. No bulky LCDs or OLED panels needed!

How They Built It: Step-by-Step in Microfabrication

The magic comes from a careful mix of additive and subtractive microfabrication techniques. Here’s a simplified breakdown of how the team made it happen:

1. Designing the Circuit
  • The LED driver circuit was created using EasyEDA (a Printed Circuit Board design tool).
  • The design was converted into a format suitable for inkjet printing.
2. Printing on Kapton
  • They used DuPont Kapton® 500B, a black polyimide film known for its strength, flexibility, and heat resistance.
  • Silver nanoparticle ink was inkjet-printed onto the film to form conductive tracks.
  • The substrate was heated (first at 50 °C, then at 200 °C) to “sinter” the ink, ensuring electrical conductivity.
3. Aligning the Layers

Since the circuit was double-sided, alignment was crucial:

  • Fiducial markers (small square reference points) were printed and laser-cut into the Kapton.
  • These markers allowed precise alignment when printing the bottom layer and drilling vias (tiny holes connecting the two layers).
4. Creating Vias
  • Using a laser system, they cut 441 tiny holes (0.31 mm diameter each).
  • These were then filled with conductive paste to electrically connect both layers.
  • The board was reheated to cure the connections.
5. Adding Components
  • Surface-mount components (like resistors and drivers) were added using semi-automatic pick-and-place tools.
  • A microcontroller was connected to manage the LED patterns and update the QR code in real time.
  • The result? A flexible, fully functional e-QR display that can be scanned with an ordinary smartphone.
What Did They Achieve?

The team successfully demonstrated:

  • A working 21 Ă— 21 LED matrix on flexible Kapton.
  • Reliable vias — all 441 laser-drilled holes connected the top and bottom layers without issue.
  • Dynamic QR display — capable of encoding real-time sensor data into a scannable electronic QR code.

This proves that microfabrication + printed electronics can yield functional, low-cost display systems without the need for traditional, resource-hungry display technologies.

Why It Matters: Beyond Lab Prototypes

Let’s break down why this is such a game-changer:

Cost Efficiency
  • No need for large-scale wireless IoT setups.
  • Uses cheap, scalable printed electronics instead of silicon-heavy circuits.
Flexibility & Durability

Kapton substrates bend without breaking, opening doors for wearables, smart labels, and portable sensors.

Accessibility

Any smartphone with a camera can read the data—no special equipment needed.

Citizen Science Potential

Imagine communities deploying low-cost air-quality monitors, where volunteers simply scan e-QR codes around their neighborhood to contribute data.

Future Prospects for Printed e-QR Codes

The researchers see plenty of room for improvement:

  1. Digital Additive Manufacturing: Instead of using stencils for solder paste, future systems could rely entirely on digital printing—boosting scalability.
  2. Dielectric Printing: Printing insulating layers with built-in via holes could streamline the process.
  3. Scaling Up: More pixels = higher QR code versions = more data capacity. Imagine dynamic QR codes that can carry larger datasets.
  4. Wearables & Smart Packaging: Flexible e-QRs could be embedded in clothing, medical patches, or even food packaging, updating freshness or usage data in real time.
  5. IoT Without the “I”: By bypassing constant internet connections, these displays could create localized data-sharing ecosystems, especially useful in resource-constrained regions.
The Road Ahead

This work represents a bridge between traditional IoT sensors and next-gen printed electronics. By embedding intelligence into something as simple and universal as a QR code, the team has opened possibilities for:

  • Smart cities that monitor infrastructure with scannable tags.
  • Healthcare devices that update status with a quick scan.
  • Supply chains that offer live product condition updates.

It’s a prime example of how microfabrication doesn’t just shrink technology—it makes it more accessible, sustainable, and human-friendly.

Wrapping Up

The University of Pretoria’s demonstration of a microfabricated e-QR code on Kapton shows us a future where printed electronics meet everyday life. By turning QR codes into dynamic, flexible displays, they’ve transformed a familiar technology into a powerful, low-cost tool for sharing real-time information.

Next time you scan a QR code, imagine it’s not just a static link, but a living, glowing window into real-world data.


In Terms

Microfabrication - The science of making really tiny structures—like circuits and sensors—on a microscopic scale, often using special printing, etching, or laser techniques. Think of it as miniaturized manufacturing.

Printed Electronics - Electronics made by “printing” conductive materials (like silver inks) onto surfaces, instead of traditional silicon chipmaking. It’s like 3D printing, but for circuits! - More about this concept in the article "Revolutionizing Diabetes Care: The 3D-Printed Sensor Changing Glucose Monitoring".

Electronic QR Code (e-QR) - A QR code made of electronic pixels (like LEDs) instead of just ink on paper. These can change in real time, displaying new information that your phone can still scan.

Flexible Substrate - A bendable material (like plastic films or polyimide sheets) that circuits can be built on. Unlike rigid circuit boards, these can twist and flex without breaking.

Kapton - A tough, heat-resistant plastic film often used in electronics. Imagine a super-thin, bendable sheet that can survive high temperatures—perfect for flexible circuits.

Via - Tiny holes drilled into a circuit board that connect different layers together, letting electricity flow between them—like mini “elevators” for electrons.

Fiducial Markers - Small printed reference points used to align different layers of a circuit during manufacturing. Basically, “guide dots” that help keep everything lined up.

LED Matrix - A grid of tiny LEDs arranged in rows and columns, where each LED can turn on or off to create patterns, images, or in this case, a QR code.

IoT (Internet of Things) - A network of everyday objects (sensors, appliances, wearables) that collect and share data online. Your smart watch or smart thermostat? That’s IoT in action. - More about this concept in the article "Digital Twin Boosts Vertical Farming".


Source

Raju, A.E.; Laue, H.E.A.; Joubert, T.-H. Microfabrication of an e-QR Code Sensor Display on a Flexible Substrate. Eng. Proc. 2025, 109, 16. https://doi.org/10.3390/engproc2025109016

From: University of Pretoria.

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