A low-power LAMP device with chemical heating and compact optical detection for point-of-care testing

A fully portable device featuring electricity-free heating was developed for conducting loop-mediated isothermal amplification (LAMP) and reverse transcription LAMP (RT-LAMP), enabling rapid nucleic acid detection in resource-limited settings. The system utilizes a chemical heating module powered by the exothermic reaction between calcium oxide (CaO) and water, in conjunction with a palmitic acid-based phase-change material (PCM) that maintains a stable reaction temperature within the optimal DNA amplification range of 60°C-65 °C. DNA amplification is monitored in real time via SYTO-9 fluorescence using a compact optical detection module consisting of a low-power blue light-emitting diode (LED) and a photodiode. Analytical performance of the system was evaluated using human genomic DNA (BRCA1) and synthetic SARS-CoV-2 RNA as model targets. The device exhibited excellent linearity in SYTO-9 fluorescence detection (R² = 0.989-0.993) and a lower limit of detection (LOD; 0.010-0.026 μM) compared to a commercial microplate reader (R² = 0.981, LOD = 0.061 μM). For RT-LAMP assays, the device achieved an LOD of 1.025 copies/reaction for SARS-CoV-2 RNA. Specificity testing confirmed the absence of false-positive signals from saliva or non-target RNA samples. Owing to its compact size, electricity-free thermal control, and high analytical sensitivity, the developed device offers a promising platform for point-of-care diagnostics, especially in emergency response and off-grid environments.