# Handheld Lab-on-a-Chip System for Label-Free Dual-Plex Detection of Biomarkers Through On-Chip Plasma Separation

## TL;DR

A handheld device was developed to detect multiple biomarkers in blood quickly and without labels, enabling on-site diagnostics.

## Contribution

A novel handheld lab-on-a-chip system with integrated plasma separation and dual-plex label-free biosensing is introduced.

## Key findings

- The system can detect albumin and creatinine in whole blood with high sensitivity and specificity.
- The device achieves detection limits as low as 0.8 μg/mL for albumin and 1.44 μg/mL for creatinine.
- The platform shows minimal nonspecific binding and reliable performance in real-world sample conditions.

## Abstract

Rapid and reliable detection of biomarkers in complex fluids such as whole blood is essential for effective disease diagnosis and monitoring, particularly in point-of-care settings. Accordingly, this study developed a handheld lab-on-a-chip (LOC) platform that integrates on-chip plasma separation with label-free optical biosensing for real-time, dual-plex detection of biomarkers. The LOC platform includes a two-stage filtration unit that enables efficient separation of plasma from whole blood. This platform also includes a novel gradient grating period guided-mode resonance sensor array that is capable of simultaneously detecting multiple biomarkers with high sensitivity. A compact handheld reader was developed to acquire and analyze optical signals. By using creatinine and albumin as model biomarkers, we demonstrated that the developed platform could achieve sensitive, specific, and reproducible biomarker detection in both plasma and whole-blood samples. The platform can detect albumin and creatinine at concentrations as low as 0.8 and 1.44 μg/mL, respectively, and it exhibits minimal nonspecific binding. These results highlight the potential of the proposed system as a robust and accessible tool for decentralized diagnostics.