The device was designed to look for and trap different types of bacteria and find out which antibiotics are most effective against them. Rather than growing bacterial cultures then testing them, the microscopic device relies on nano-scale technology for fast results.
The main feature of the device is a cantilever, a plank that resembles a diving board that has a microfluidic channel 25 times smaller than the width of a hair etched on its surface. The channel is coated with biomaterials, like antibodies, that harmful bacteria like E. coli or Listeria in fluid samples stick to.
When bacteria are caught, the device sends out three different signals to the researchers. When bacteria is detected, the cantilever’s mass changes, and it bends, explained researcher Thomas Thundat.
“So, this gives us two signals: the mass change and the bending action by shining infrared light on the bacteria, a third signal is sent. If the bacterial absorbs the light, it begins to vibrate, generating a minute amount of heat that sends a confirmation signal. Having three detection methods means there is no ambiguity”.
“By monitoring the interaction of light and bacteria, we can get highly selective detection of bacteria,” said Faheem Khan, another expert.
With the bacteria trapped in the cantilever, different antibiotic drugs can be added to the device. Changes in the intensity of tiny oscillations of the cantilever signal will inform the researchers whether the bacteria are alive or dead. The researchers then know which antibiotics the bacteria are susceptible to.
“We’re trying to find a way to fight bacterial resistance to drugs and prevent or at least decrease the spread of drug-resistant strains,” said Hashem Etayash, a researcher. Adding, “We’re able to do several tests in a very short period of time and we can quickly identify bugs that can resist antibiotics.”
The device can be used to test extremely small fluid samples, millions of times smaller than a rain droplet. The size of the device is advantageous when you only want a very small sample, in settings such as a neonatal intensive care unit, or in situations where only very small samples are available.
The research was published in Nature Communications journal.