Practically each trendy cellphone has a built-in compass, or magnetometer, that detects the path of Earth’s magnetic discipline, offering essential info for navigation. Now a workforce of researchers on the Nationwide Institute of Requirements and Know-how (NIST) has developed a way that makes use of an abnormal cellphone magnetometer for a completely completely different goal — to measure the focus of glucose, a marker for diabetes, to excessive accuracy.
The identical method, which makes use of the magnetometer along side magnetic supplies designed to alter their form in response to organic or environmental cues, could possibly be used to quickly and cheaply measure a bunch of different biomedical properties for monitoring or diagnosing human illness. The strategy additionally has the potential to detect environmental toxins, mentioned NIST scientist Gary Zabow.
Of their proof-of-concept examine, Zabow and fellow NIST researcher Mark Ferris clamped to a cellphone a tiny nicely containing the answer to be examined and a strip of hydrogel — a porous materials that swells when immersed in water. The researchers embedded tiny magnetic particles throughout the hydrogel, which they’d engineered to react both to the presence of glucose or to pH ranges (a measure of acidity) by increasing or contracting. Altering pH ranges may be related to quite a lot of organic problems.
Because the hydrogels enlarged or shrunk, they moved the magnetic particles nearer to or farther from the cellphone’s magnetometer, which detected the corresponding adjustments within the energy of the magnetic discipline. Using this technique, the researchers measured glucose concentrations as small as a couple of millionths of a mole (the scientific unit for a sure variety of atoms or molecules in a substance). Though such excessive sensitivity shouldn’t be required for at-home monitoring of glucose ranges utilizing a drop of blood, it’d sooner or later allow routine testing for glucose in saliva, which comprises a a lot smaller focus of the sugar.
The researchers reported their findings within the March 30, 2024 version of Nature Communications.
Engineered, or “good,” hydrogels like those the NIST workforce employed are cheap and comparatively straightforward to manufacture, Ferris mentioned, and may be tailor-made to react to a bunch of various compounds that medical researchers could need to measure. Of their experiments, he and Zabow stacked single layers of two completely different hydrogels, every of which contracted and expanded at completely different charges in response to pH or glucose. These bilayers amplified the movement of the hydrogels, making it simpler for the magnetometer to trace adjustments in magnetic discipline energy.
As a result of the method doesn’t require any electronics or energy supply past that of the cellphone nor name for any particular processing of the pattern, it gives a cheap method to conduct testing — even in areas with comparatively few sources.
Future efforts to enhance the accuracy of such measurements utilizing cellphone magnetometers may enable detection of DNA strands, particular proteins and histamines — compounds concerned within the physique’s immune response — at concentrations as little as a couple of tens of nanomoles (billionths of a mole).
That enchancment may have substantial profit. As an example, measuring histamines, that are sometimes detected in urine at concentrations starting from about 45 to 190 nanomoles, would ordinarily require a 24-hour urine assortment and a complicated laboratory evaluation.
“An at-home take a look at utilizing a cellphone magnetometer delicate to nanomolar concentrations would enable measurements to be finished with a lot much less problem,” mentioned Ferris. Extra usually, enhanced sensitivity can be important when solely a small quantity of a substance is out there for testing in extraordinarily dilute portions, Zabow added.
Equally, the workforce’s examine suggests {that a} cellphone magnetometer can measure pH ranges with the identical sensitivity as a thousand-dollar benchtop meter however at a fraction of the associated fee. A house-brewer or a baker may use the magnetometer to rapidly take a look at the pH of varied liquids to excellent their craft, and an environmental scientist may measure the pH of floor water samples on-site with greater accuracy than a litmus take a look at strip may present.
With a purpose to make the cellphone measurements a business success, engineers might want to develop a technique to mass produce the hydrogel take a look at strips and be sure that they’ve a protracted shelf life, Zabow mentioned. Ideally, he added, the hydrogel strips needs to be designed to react extra rapidly to environmental cues with a view to velocity up measurements.
