The ‘lab-on-chip’ device is entirely self-powered, using pressure differences and gravity to separate components of a small blood sample.
Microfluidic technologies have been touted for some time, and while small devices have been demonstrated, they typically rely on large and expensive external equipment such as compressors and various electronic components.
This essentially renders them unsuitable for applicatioons such as point-of-care diagnostics and field work in developing nations.
Aiming for a simpler approach, a team from Dublin City University and University of California, Berkeley designed a device incorporating micro-scale channels and trenches powered by a process called degas-driven flow.
After manufacture, all air is removed from the device – creating an internal vacuum – and it is then sealed and stored. When ready for use the seal is ripped of and a blood sample is placed in the end wells, which creates a pressure gradient forcing the blood horizontally across the channels.
Crucially, along the bottom of the channels are trenches, which collect the denser red blood cells as they sink along their journey through the channels.
This effectively separates the blood plasma which travels to the end of the channels where molecular sensors can detect plasma-residing proteins, such as the HIV antigen.
‘It is versatile, simple, efficient and cheap. It can be applied to fabricate a plethora of new point-of-care diagnostic tests with very high sensitivity at very low cost,’ said Dr Lourdes Desmonts of Dublin.
If you had something as cheap and easy to use as a pregnancy test It could save millions of lives
Benjamin Ross, University of California
Indeed, the team claims the sensors can be easily adapted to detect different protein molecules and thus pathological conditions. In a proof-of-concept study the device was able to detect 1.5pM of biotin (vitamin B7) in 5 microliters whole-blood samples.
In practice the device should reduce the likelihood of sample contamination, increase result reproducibility and quality, and help eliminate errors due to sample handling.
‘Imagine if you had something as cheap and as easy to use as a pregnancy test, but that could quickly diagnose HIV or TB. That would be a real game-changer. It could save millions of lives,’ said Benjamin Ross of Berkeley.