Researchers have developed a low-cost, microfluidic electrochemical biosensor that enables accurate, on-site CD4+ T cell counting for HIV monitoring in low-resource settings.
Microfluidic Biosensor CD4+ T-Cells. Image Credit: Microsystems & Nanoengineering
Accurate monitoring of CD4+ T cell counts is essential for assessing immune function and guiding treatment decisions in individuals living with HIV. While flow cytometry remains the gold standard, its high cost, complexity, and reliance on laboratory infrastructure make it impractical for widespread use in remote or resource-limited settings.
Portable alternatives exist, but many fall short due to low sensitivity, complex handling requirements, or high operating costs. Optical and fluorescence-based systems, although technically advanced, often bring additional maintenance burdens and equipment demands.
Recognizing these challenges, a team of researchers from the University of Bath and Nanyang Technological University has developed an integrated microfluidic electrochemical biosensor designed specifically for low-resource environments. Their work, published in Microsystems & Nanoengineering, introduces a polydimethylsiloxane (PDMS) chip with embedded gold electrodes that enables label-free, impedance-based detection of CD4+ T cells. Engineered for simplicity and efficiency, the device minimizes sample handling and delivers clinically relevant results quickly—an important step toward accessible, real-time HIV diagnostics outside traditional labs.
At the heart of the system is a microfluidic chip where both cell capture and detection occur. Anti-CD4 antibodies are immobilized via self-assembled monolayers on the gold electrodes, allowing for selective binding of target cells.
The biosensor's wide dynamic range can detect both low and normal CD4+ levels, making it useful across a spectrum of patient conditions. Its detection threshold is sensitive enough to identify severe immunodeficiency, while the microfluidic format reduces variability and manual input, enhancing reproducibility and automation potential. Specificity tests confirmed minimal interference from other immune cells and serum proteins. Additionally, the sensor can be coupled with a Dean Flow Fractionation (DFF) chip for upstream cell separation, enabling a modular setup that combines isolation, capture, and analysis on a single device.
Our goal was to develop a user-friendly, affordable diagnostic tool that could extend high-quality HIV monitoring beyond centralized labs. By combining electrochemical sensing with microfluidics, we have created a platform that is not only accurate and sensitive, but also scalable and compatible with point-of-care use. This technology has the potential to democratize access to HIV diagnostics, especially in regions with limited medical infrastructure.
Pedro Estrela, Study Corresponding Author and Professor, University of Bath
Looking ahead, the team envisions this microfluidic biosensor as a practical solution for HIV monitoring in underserved regions, replacing large, stationary lab equipment with compact, battery-powered alternatives. The platform's flexible design supports automated sample processing and could be adapted to detect other immune markers or infectious agents.
Future development plans include integrating the DFF module for whole blood analysis, conducting clinical validation, and refining the interface for field-ready deployment. In the long term, the technology may help expand access to early diagnosis and improve treatment monitoring, contributing to more equitable healthcare in the global effort to manage HIV.
Journal Reference:
Białas, K. et al. (2025) Electrochemical microfluidic biosensor for the detection of CD4+ T cells. Microsystems & Nanoengineering. doi.org/10.1038/s41893-025-01559-z