A smartphone-powered decentralized microfluidic platform for sensitive CRISPR-based nucleic acid detection

Sensitive, portable, and low-cost nucleic acid detection without need for complicated equipment or trained operators, allows flexibility in forward (i.e., near the point of collection) detection and diagnostics that could be applied in resource-limited settings. To this end, we developed a microfluidic, chip-based laser-induced graphene (LIG) heater with precise temperature control for loop-mediated isothermal amplification (LAMP) of DNA or RNA and subsequent CRISPR/Cas9-based molecular interrogation. Detection was pursued using commercial lateral flow assays (LFAs) and an ultrasensitive electrochemical module that utilizes Hexaammineruthenium (III) chloride (RuHex) as a redox probe. Using LIG-based LAMP amplification we were able to amplify and detect targets in samples with as low as 5 copies per 10 μL. We also evaluated post amplification products to determine the threshold amount of analyte required to enable detection. Our device demonstrated detection limits of 10¹¹ for LFA and 5 × 10⁶ copies μL⁻¹ for the electrochemical platform. An integrated Arduino-based control unit was developed for housing the amplification and detection components of the diagnostic suite, such that it operates solely on smartphone power with steady-state power consumption of approximately 130 mW for the LIG heater. The approach represents a low-cost, low-power diagnostic platform with potential for point-of-care application.