Filtration & fl uid control
slides before being heated for around a minute to bind them to the glass. This produces a microfluidic chip master mould. Next, the slides are rapidly cooled on a metal plate before being removed from the mould. The researchers can then use and reuse the master to produce devices made from PDMS. Once the scaffolds emerge from the printer, the master-mould fabrication process takes a matter of minutes, Hughes reveals.
The team managed to print channels 100µm in diameter, which they say is a marked improvement over the standard 3D printing channel resolution. They anticipate the resolutions improving as the field of MEX 3D printing continues to evolve.
Teaching tool
“This technique is so simple, quick and cheap that devices can be fabricated using only everyday domestic or educational appliances and at a negligible cost,” said Felton in the paper’s accompanying press release. “This means researchers and clinicians could use our technique and resources to help fabricate rapid medical diagnostic tools, quickly and cheaply, with minimal additional expertise or resources required.” Clinicians in resource-poor countries would be able to apply the channels directly to any cleaned glass surface, such as a mobile phone screen or car windshield for resourceful point-of-care testing, he added. The Bristol team say whole libraries of interconnecting channel moulds can be manufactured so cheaply that they can even be used as an educational tool in schools. Hobbyists could make LOC devices using only household equipment with no need for hazardous chemicals. And using the Bristol- developed plug-in, a user can go from a microfluidic channel design to a completed 3D channel without needing CAD software expertise.
The Bristol team now hope to identify potential collaborators in both research and education to help
A fidget spinner for UTIs
A multidisciplinary and international team of Korean and Indian researchers developed a fi dget spinner-based device to detect UTIs from urine samples. The rectangular device, which takes as little as 1ml of urine, was designed to be made cheaply for use in resource-limited settings. One or two nudges causes the device spins for a long time, the motion of which pushes any bacteria on to a membrane. It is then dyed, with a colour change visible in less than one hour that indicates the amount of bacterial load. The spinner was fi eld tested on 39 patients in Tiruchirappalli, India, all of which would have been given antibiotics based on their symptoms. The researchers found that 59% of the patients were found to be over or under-treated with antibiotics. Another test gave an initial indication of antibiotic resistance by testing the spun samples treated with different drugs and comparing them to untreated samples. The team was able to quickly decide on which antibiotic might work best to treat the UTI. While this does not compare to lab-based tests, the researchers noted in their paper published in the journal Nature Biomedical Engineering that it is still a useful tool for resource-limited areas that do not typically test for resistance. The further development of centrifuge-based microfl uidics may enable the acceleration of each of the steps of bacterial infection diagnostics, eliminating the need for multiple devices and enabling on-site diagnostics, signifi cantly reducing diagnostic time and overall costs.
demonstrate the impact the manufacturing technology can have for both medical settings and outreach activities. An obvious next step is to manufacture a specific point-of-care medical test using the team’s 3D-printing technique and test its sensitivity and specificity. Hughes’ team is working with chemists at the university to help make this pursuit a reality.
“Researchers and clinicians could use our technique and resources to help fabricate rapid medical diagnostic tools, quickly and cheaply, with minimal additional expertise or resources required.”
Harry Felton, University of Bristol
“My hope is that we can inspire a whole generation of people about microfluidics,” says Hughes. “I think it’s a fascinating area and I certainly think it’s going to underpin a lot of medical diagnostics in the future.” ●
The Bristol team developed a more accessible way to manufacture microfl uidic chips using a desktop MEX 3D printer.
Medical Device Developments /
www.nsmedicaldevices.com 97
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