Mechanical Timer-Actuated Fluidic Dispensing System: Applications to an Automated Multistep Lateral Flow Immunoassay with High Sensitivity

Abstract

In this study, we present a fluidic dispensing system that can automate the sequential fluidic delivery of multiple reagents for lateral flow assays. Highly sensitive assays typically require multiple solution-based sequences, including washing steps and signal amplification. However, implementation of these types of sequences on an automated and highly sensitive point-of-care testing (POCT) platform remains challenging. Our platform consists of two disposable cartridges with reagent chambers and a test strip and an instrument that has a mechanical timer to actuate the cam–follower–gear components. The timer rotation sequentially shifts the position of the chambers and loads the reagents to the test paper strip. The dispensing intervals are controlled at a variation of <1% within a total actuation time of 60 min. Unlike other POCT devices, the timing of fluid delivery in our timer-actuated platform is not dependent on the selection of substrates and reagents, and the unique approach to fluidic delivery results in no reagent overlap or carryover, minimal reagent loss, and highly accurate fluidic timing control for highly sensitive solution-based assays. As a model application, the proposed platform applies a gold enhancement solution to amplify the detection signal and detect prostate-specific antigen with a limit of detection of 86 pg/mL within 27 min. This platform provides an opportunity for solution-based POCT applications with high sensitivity, thereby satisfying the requirement for user-friendly operations in resource-limited settings.

Improved sensitivity and automation of a multi-step upconversion lateral flow immunoassay using a 3D-printed actuation mechanism

“…To automate a multi-step LFA, the liquid processing has been executed via mechanical kitchen timers. This enables reusable electricity free system with low cost and poses little to no modification needs to the LF strips themselves [ 10 , 11 ].…”

Enhanced NIR-II Fluorescent Lateral Flow Biosensing Platform Based on Supramolecular Host–Guest Self-Assembly for Point-of-Care Testing of Tumor Biomarkers

“…For instance, prostate-specific antigen (PSA) is a serum biomarker that is widely used for the screening, diagnosis, and treatment of prostate cancer (PCa). , A total PSA level of 4.0 ng mL –1 (more recently 2.5 ng mL –1 ) is a highly probable indication for PCa. , Conventional detection methods for tumor biomarkers mainly include enzyme-linked immunosorbent assay, chemiluminescence immunoassay (CLIA), and electrochemical immunoassay . These methods are performed in centralized laboratories equipped with large-scale automated analyzers and skilled operators as well as tedious assay procedures, which are not suitable for primary care and fast diagnosis. − Therefore, there are increasing demands for the development of diagnostic tools for the detection of tumor biomarkers with high sensitivity, accuracy, rapidness, and low cost.…”