New York - A miniaturized “lab-on-a-chip” test, which draws its power from the headphone jack of smartphone, can perform three antibody tests within 15 minutes. In first field study in Science Translational Medicine (2015; 7: 273re1) it has proven to be an inexpensive mini-laboratory for diagnosing HIV and syphilis.
Laboratory diagnosis of HIV and syphilis is usually carried out by detecting antibodies in the Serum. In the HIV test, they are directed directly against the virus, while non-treponemal antibodies are detected in addition to Treponema-specific antibodies to diagnose syphilis. In total, this results in three tests that are usually carried out in the laboratory with ELISAs.
A conventional ELISA shows the antibodies in multi-phase test using an enzymatic color reaction. The ELISA devices are relatively bulky, cost around 20,000 euros to purchase and require electricity to operate, which often makes them difficult to use in remote regions of Africa. Due to the necessary transport of the blood samples, days can pass before the results arrive.
As portable “Lab-on-a -chip "systems (LOCs) are functional systems that integrate various laboratory diagnostic procedures on one chip and are characterized by miniaturization, parallelization and diversification.
A" Lab- on-a-chip ”test, developed by Samuel Sia's team from Columbia University in New York and employees, is the size of credit card and it shortens the verification time to around 15 minutes. The core of the mChip (“mobile microfluidic chip”) are small capillaries, on the inner walls of which in principle chemical reactions take place similar to those of the ELISA.
The cost of an mChip is only about 34 US dollars. However, it is single-use item, whereas an ELISA device with new chemicals can be used several times and can also examine the samples of many test subjects at the same time.
. It has now been refined again for use in Rwanda. In order to minimize power consumption, the serum is now sucked into the potash using "one-push vacuum". The little energy that the mChip still needs is now drawn from smartphone via the headphone output.
Since this "audio jack" is internationally standardized, the device can be used on all smartphones (iPhones and Androids) . The smartphone also makes it easier to operate the mChip via the alarm function. It can also save the results and forward them if necessary. The “dongle” developed by Sia does not require any additional power supply and can therefore also be operated in areas without power lines (as long as the smartphone's battery is charged).
In first field test in Rwanda, the mChip achieved detection of HIV and syphilis sensitivity of 92 to 100 percent and specificity of 79 to 100 percent. The test does not achieve the reliability of an ELISA, but it could be suitable for screening. It's easy to use. The health workers in Rwanda only required 30-minute briefing. 97 of those tested also said that they would prefer the test because of the quick results and ease of use.