Portable Low-Cost Fluorescence Reader for LFA Measurements

Abstract

A portable device for measuring fluorescence signals from a lateral flow test strip was developed. The aim was to build an easy-to-use, affordable reader device for fast, quantitative analysis of point-of-care tests, made mostly of commercial off-the-shelf components. The device is capable of exciting fluorescent labels with 532 nm and 650 nm lasers and collecting the emitted fluorescent light with a camera. Core of the device is a Raspberry Pi Zero W wireless single board computer that controls the Raspberry Pi camera v2 module and lasers. The computer can also perform the image analysis and communicate the results to a mobile phone application acting as a user interface. Sensitivity of the device was characterized by sweeping the imaging parameters and comparing the performance with a high-grade fluorescence reader. Using dummy LFA samples, it was found that the device is able to detect signals from analyte concentrations that are relevant in biological samples. Image exposure time of $500~\mu \text{s}$ was enough to read a distinguishable signal. The manufacturing costs were estimated to be below 100 euros per device in mass production.