Precision chemical heating for diagnostic devices

Abstract

Decoupling nucleic acid amplification assays from infrastructure requirements such as grid electricity is critical for providing effective diagnosis and treatment at the point of care in low-resource settings. Here, we outline a complete strategy for the design of electricity-free precision heaters compatible with medical diagnostic applications requiring isothermal conditions, including nucleic acid amplification and lysis. Low-cost, highly energy dense components with better end-of-life disposal options than conventional batteries are proposed as an alternative to conventional heating methods to satisfy the unique needs of point of care use.

Single-use paper-based hydrogen fuel cells for point-of-care diagnostic applications

“…This temperature profile agrees with observations in previous chemical heaters studies using this reaction. [37][38][39] The average peak temperature for all tested combinations is 30.0 ± 2.8 °C. Higher NaCl concentrations result in higher peak temperatures.…”

“…Previous studies of chemical heaters using the MgFe reaction have highlighted parameters which affect the heat production. [39] Here we evaluate the effect of two of the most influential variables in both heat and hydrogen production, i.e. the amount of NaCl as electrolyte (both stored in solid form and supplied in solution) and the amount of MgFe stored in the device.…”

“…The duration of the power delivery can be extended as these devices use up to 20x more MgFe for a single test (and consequently, produce as much hydrogen) than the amount used in the fuel cells presented here. [39][40][41][42] This approach implies reusability of the fuel cells for more than one measurement, thus reducing the overall cost per test.…”

“…the corrosion of magnesium iron particles. [36][37][38][39][40][41][42] This chemistry is very convenient, as it , requires only the addition of water to achieve 100°C (a reason why it has also been widely used to heat portable meals). During the course of the chemical reaction the magnesium is oxidized, releasing hydrogen gas as a byproduct, which previously was simply vented off to the atmosphere.…”

Direct colorimetric LAMP assay for in-field detection of African swine fever virus: a validation study during an outbreak in Vietnam

“…All those advantages make LAMP an excellent isothermal nucleic acid amplification technique which has been broadly utilized currently. Besides, to supply stable heat for amplification reactions, numerous electricity-free and portable devices were developed, allowing the simpler application of LAMP at field usage (Buser et al, 2015; Shah et al, 2015; Singleton et al, 2014; Singleton et al, 2013). In this study, we developed a rapid test kit based on colorimetric LAMP assay for the detection of ASFV utilizing a pH-sensitive dye for readout visualization.…”