Collecting blood and urine specimens can often be messy or painful for patients. And for legally sensitive tests, such as for drugs or alcohol, ensuring the sample’s integrity demands close supervision at the expense of privacy.
So there’s understandable biotech buzz about a trio of new testing devices that use saliva and teardrops to measure diabetics’ sugar levels, or the sweat in fingerprints to detect illicit drugs.
Some 350 million people worldwide, including 26 million Americans, have diabetes, and most need to monitor their blood-sugar levels several times a day to make sure they’re keeping it in a safe range with diet or medications.
Hand-held meters require a drop of blood, usually obtained by pricking a patient’s fingers with a pin or lancet — a process painful enough for some to discourage regular checking.
Engineers at Brown University have designed a fingernail-sized biochip etched with thousands of light-measuring devices to gather information about concentrations of glucose molecules in solution. Changes in light intensity transmitted through each sensor provide information about the concentrations of glucose in the sample.
Testing the devices with water, researchers have been able to detect glucose at levels similar to those found in human saliva. Those levels are typically about 100 times less concentrated than in human blood.
The team, led by Domenico Pacifici, an assistant professor of engineering, reported its work this month in the journal Nano Letters. Having confirmed the concept, the engineers are now working on building sensors that are more specifically crafted to measure glucose and other substances, from anthrax to biological compounds.
“It could be possible to use these biochips to carry out the screening of multiple biomarkers for individual patients, all at once and in parallel,’’ Pacifici said.
At the University of Michigan, researchers reported in November that they’ve been able to use glucose levels in tears to give the same level of detail that comes from blood testing. The study in the journal Analytical Chemistry was based on work with rabbits, but the same sensor array is expected to work in humans.
The scientists say it will be several years before any tear-monitoring kit will be available commercially for people.
Even then, they’ll recommend that patients back up the device with a blood test before taking insulin. Several other institutions are also working on glucose testing with teardrops.
In Norwich, England, Intelligent Fingerprinting Ltd. — a company founded by researchers at the University of East Anglia — is coming to market with a device able to detect drugs and other illicit substances from the sweat contained in fingerprints.
The hand-held devices are able to both scan a fingerprint for positive identification and analyze the sweat for drug byproducts in a matter of minutes. David Russell, the company’s chief technical officer and an East Anglia chemistry professor, said the device’s first models will focus on abused drugs and likely will be shipped later this year. He said researchers also are working to expand the scope to detect therapeutic drugs and other biological markers released in sweat.
Lee Bowman is a health and science writer for Scripps Howard News Service. Reach Bowman at BowmanL@shns.com