Smartphones using magnetic particles in hydrogels and the built-in compass can measure glucose, pH levels, toxins, and other biomarkers for disease detection. NIST researchers demonstrated this technique, allowing for high accuracy glucose measurements using an ordinary cellphone magnetometer. The hydrogels, engineered to react to specific substances, expand or contract affecting the magnetic particles’ distance from the magnetometer. This method is affordable, requiring no additional power or electronics, making it ideal for widespread testing. The researchers also anticipate further advancements to measure DNA strands, proteins, and histamines at extremely low concentrations, suggesting significant potential for future medical and environmental applications.
https://www.nist.gov/news-events/news/2024/04/nist-researchers-use-cellphone-compass-measure-tiny-concentrations