3D-printed sensors versus foodborne pathogens: A closer look

There’s no way to put a good spin on it: Food-product recalls are a very bad thing.

Often caused because of some sort of contamination, a recall has the domino effect of triggering doubts in the minds of consumers about the safety, and then the reliability, of what they eat and drink.

And it’s actually worse than that: In many cases, a recall will come too late to keep some people from having already gotten ill, perhaps even fatally so. According to the World Health Organization, “unsafe” food causes 600 million cases and 420,000 deaths annually, with at least a third occurring in children under 5 years of age. Pregnant women and older adults, in particular, are extremely susceptible to serious consequences.

And there’s an economic cost, too.

For example, the Economic Research Service, which is a part of the United States Department of Agriculture, estimates that foodborne illnesses caused by pathogens such as salmonella, toxoplasma gondii, listeria monocytogenes, norovirus, and campylobacter cost the American economy alone approximately US$15.5 billion annually. This enormous economic burden is associated with medical expenses and the loss of production from workers being unable to work due to the effects of food poisoning.

Researchers have created a chip with four distinct regions, capable of rapidly testing for the presence of multiple pathogens simultaneously. (a) Initial picture of the detection platform with the detection chip placed in the sensing area. (b) All four shut-valves are in operation, adding liquid to the liquid addition port. (c) Close one of the shut-valves and the liquid flows toward the sensing area. (d) Close all shut-valves and fluid flows to the perimeter sensing area.

EXISTING TECHNOLOGIES FALL SHORT
Finding contaminating pathogens is no easy task, and much of the problem stems from the tools available to screen for harmful pathogens – even the best detection methods of the modern era are often not effective enough at protecting the public.

But now, researchers from Guangdong University of Technology, in Guangdong, China, and Pudong New District People’s Hospital have developed a new method for detecting foodborne pathogens that’s said to be faster, cheaper, and more effective than existing methods.

The researchers hope their technique can improve screening processes and keep contaminated food out of the hands of consumers.

“Detecting these pathogens is challenging due to their diverse nature and the various environments in which they can thrive,” said research team member Silu Feng. “Additionally, low concentrations of pathogens in large food samples, the presence of similar non-pathogenic organisms, and the complex nature of different food types make accurate and rapid detection difficult.”

Existing detection methods – such as cell culture and DNA sequencing – do exist but are challenging to employ at large scales; not every batch of food can be thoroughly tested, so some contaminants inevitably slip through. “Overall, these methods face limitations such as lengthy result times, the need for specialized equipment and trained personnel, and challenges in detecting multiple pathogens simultaneously,” Feng said.

A NEW APPROACH
The Guangdong University researchers took a new approach: they designed a microfluidic chip that uses light to detect multiple types of pathogens simultaneously. The added benefit is that the chip is created using 3D printing, which makes it easy and cost-effective to fabricate in large amounts and modify to target specific pathogens.

The chip is split into four sections, each of which has three sensors, with each sensor having a layer of a nanopore thin film as the sensing element. The detection is based on observing optical signal shifts corresponding to the concentrations of the different foodborne pathogens – if that pathogen is present in the sample, it will bind to a detection surface and change its optical properties.

This arrangement lets the researchers detect several common bacteria – such as E. coli., salmonella, listeria, and S. aureus – quickly and at concentrations that are significantly lower than the concentration that can cause illness.

“This method can quickly and effectively detect multiple different pathogens, and the detection results are easy to interpret, significantly improving detection efficiency,” Feng said.

The team plans to continue developing their device to make it even more applicable for food screening.

This article is republished from the Summer 2024 edition of the MRO Food & Beverage ebook. Get the issue here.