Project Lead(s): Mohsen Akbari
More than 95% of tuberculosis (TB) deaths occur in low- and middle-income countries, and it is among the top five causes of death for women aged 15 to 44.
Access to current rapid and sensitive technologies in low-income countries is limited, because of their cost and complexity.
Molecular tests such as polymerase chain reaction (PCR) can be useful tools in detecting TB but current benchtop devices require electricity, which is also limited in these countries.
The goal of the project was to utilize a novel technology for the detection of pulmonary TB in low-resource countries, using polymerase chain reaction (PCR).
The project aimed to develop a thermocycler (an essential instrument for carrying out PCR) that does not require electrical power to perform all the required reactions.
An alternative method to perform thermal cycling was proposed using an exothermic chemical reaction to generate the three required temperatures on individual heating surfaces, and maintaining the same temperature on each heating surface using phase change materials (PCMs) as a heat sink.
A spring mechanical system that would repeatedly move the sample onto each heating surface would also need to be developed, as well as a miniaturized cartridge for containing the sample.
The team designed and fabricated the mechanical and controller-free thermal cycling mechanism, which is based on the Geneva Wheel mechanism and uses low-cost mechanical parts and zero-cost structural and insulation materials.
Additionally, a microfluid sample cartridge capable of containing 3 10- µL PCR samples for simultaneous analysis was designed. It was made of polydimethylsiloxane (PDMS) polymer, which is widely used in developing microchip devices.
While the team did manage to optimize the critical components of the proposed electricity-free thermocycler, they did not develop a fully functional prototype.
A heating module was developed for each target temperature, which achieved precise temperature generation that was reached in less than five minutes upon starting the chemical reaction with water, and was maintained for more than one hour.
The mechanical cycling mechanism developed is entirely mechanical and electricity-free. The team is continuing research efforts to incorporate a spring-loaded motor.
The sample cartridge chip designed can withstand continual 95°C heating for at least ten minutes, which is more than adequate for PCR analysis.
The project team will continue to develop the electricity-free thermal cycler with improved capabilities and will seek to validate the device with model samples, such as detecting non-pathogenic E. coli in buffer solutions, as well as performing tests on patient samples.
There are plans to send prototypes of the device to collaborators in India to perform field tests. The team will seek funding from governmental agencies to further develop their technology and commercialize it.