Timing Mechanism for a Low-Cost, Single Use, Nucleic Acid Amplification Diagnostic Test

Nucleic Acid Amplification Tests (NAATs) are used to diagnose infectious diseases such as tuberculosis (TB), SARS-CoV-2, and Human Papillomavirus (HPV). Conventional testing requires a bench-top system that limits its accessibility to potential patients. A self-contained, low-cost, single use NAAT would increase worldwide access to critical diagnostics. In support of an ongoing NAAT diagnostic project, we prototyped a timing mechanism to control the critical heating step that effects amplification. Herein we present a design consisting of a micro controller, a dual-channel Mosfet, and LEDs to visualize the operation. We selected electrical components that were low cost and tested the design for accuracy under two conditions: 1) the elevated temperatures required for the NAAT process and 2) a fluctuating power source, as would result from batteries suitable for a disposable device. We prototyped iteratively, ultimately demonstrating a design by creating a flex PCB approximately 3 cm by 2 cm with a cost less than 1 USD at scale. With this work, we aim to help further the development of more distributed and accessible diagnostic tests.