3D Micro-Printed Sensors to Advance On-Chip Biosensing for Early Disease Detection

Early-stage disease diagnosis depends on the ability to detect biomarkers with exceptional sensitivity and precision. However, traditional biosensing technologies struggle with achieving this at the micro-scale, especially when integrating multiple sensors into compact lab-on-a-chip systems. These limitations have slowed progress in creating real-time, low-cost diagnostic tools for early detection of diseases such as cancer and Alzheimer’s. Now, a new 3D micro-printed sensor offers a highly sensitive and scalable solution for on-chip biosensing to enable early disease detection.

Researchers at The Hong Kong Polytechnic University (PolyU, Hong Kong, China) have developed a 3D micro-printed Limacon-shaped whispering-gallery-mode (WGM) microlaser sensor that combines advanced optical resonance technology with flexible micro-printing. This innovation simplifies light coupling and boosts biosensing precision, marking a significant advance in lab-on-a-chip integration. The team leveraged PolyU’s state-of-the-art 3D micro-printing facilities to design and fabricate microcavity arrays with high speed and accuracy, overcoming long-standing technical barriers.

Image: The technology could be used for the early diagnosis of diseases such as cancers and Alzheimer\'s (Photo courtesy of PolyU)

The microlaser sensor operates by circulating light resonantly within a microcavity where even minute molecular interactions cause detectable wavelength shifts. Conventional circular WGM sensors require fragile optical fibers to capture light, limiting their practicality. The new Limacon-shaped microdisk, however, achieves directional light emission and improved coupling efficiency without external fibers. Its hybrid rigid design provides a low lasing threshold and narrow linewidth, ensuring accurate detection even at ultra-low biomarker concentrations.

In experiments, the 3D WGM microlaser biosensors demonstrated outstanding performance, with a lasing threshold of only 3.87 μJ/mm2 and a linewidth of about 30 pm. The sensors successfully detected human immunoglobulin G (IgG) — a key antibody in blood — at concentrations as low as 70 ag/mL (attograms per milliliter). These results, published in Optics Letters, highlight the device’s capability for ultra-sensitive, label-free detection and its potential role in next-generation diagnostic systems.

The innovation not only enables precise detection but also paves the way for scalable fabrication of sensor arrays for real-time biomedical analysis. Future development will focus on integrating the microlaser sensors into microfluidic chips to create fully functional optofluidic biochips capable of simultaneously identifying multiple disease biomarkers. Such systems could enable rapid diagnosis at the point of care and provide critical insights during global health emergencies.

“In the future, these WGM microlaser sensors could be integrated into a microfluidic chip to enable a new generation of lab-on-a-chip devices for ultrasensitive, quantitative detection of multiple biomarkers,” said Professor Zhang A-ping, Department of Electrical and Electronic Engineering, The Hong Kong Polytechnic University. “This technology could be used for the early diagnosis of diseases such as cancers and Alzheimer’s disease, or for fighting major health crises such as the COVID-19 pandemic.”

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