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A disposable self-heating cartridge for point-of-care molecular diagnostics

A water-activated, self-heating, instrument-free microfluidic diagnostic cartridge

Problem:

Many molecular diagnostic devices require elevated temperatures to carry out biochemical reactions, such as those needed for nucleic acid amplification, including loop-mediated isothermal amplification (LAMP). The temperature is typically regulated with external electrical power, controller, and heating elements, which increases cost and complexity. Lateral flow immunoassays, while offering straightforward and rapid detection, suffer from low sensitivity and specificity.

Solution:

Researchers in the Bau Lab have developed a point-of-care microfluidic diagnostic cartridge that can amplify nucleic acids isothermally with high specificity. The device is integrated with an exothermic heater and temperature regulator that provides a steady temperature without needing external electric power. A porous paper strip determines the rate of water supply for heater activation, triggered by an exothermic reaction with a magnesium alloy. A phase-change material of paraffin is embedded in the cartridge to maintain the temperature at the desired level, i.e., 60oC-65oC for LAMP. The cartridge utility has been demonstrated by amplifying and detecting E. coli DNA using LAMP, detecting as few as 10 molecules in a sample.

Advantages:

Self-contained device without specialized instrumentation or electricity
Maintain consistent desired temperature independent of ambient temperature
Use in clinic, home, field, or resource-poor settings
Low-cost disposable device

Applications:

Cartridge for isothermal nucleic acid amplification and visual fluorescent or colorimetric detection
Point-of-care diagnostic device
Detect viruses, bacteria, and pathogens borne in bodily fluids

From Liu et al, 2011. Photograph of water-activated, self-heating, non-instrumented cartridge for isothermal amplification of nucleic acids.