Work

Smart hydrogels with order-of-magnitude enhanced sensitivity for smartphone compass-based chemical sensing

Year: 2025

Type: article

Abstract: Smartphone-based platforms have the potential to provide low-cost and accessible measurement tools. Magnetometer-based smartphone diagnostics, which use the phone compass as signal transducer, are a newly presented possibility that complements existing optical options, which use the phone camera. With the use of motion-amplifying bilayer hydrogel actuators to translate chemical concentrations into changes in magnetic field strengths, magnetometer-based smartphone diagnostics achieve high sensitivity with low cost. Here, we further enhance the sensitivity of such platforms, confirming prior predictions of a quadratic dependence between bilayer length and sensitivity, achieving an order-of-magnitude gain in sensitivity over prior work. The technique is demonstrated on pH hydrogel actuators, but since it requires changing only the geometry of the actuator, it can be applied universally, regardless of the target analyte. A full analytical model of sensor response is also presented, suggesting additional prospects for increasing sensitivity and control over sensor dynamic and linear ranges. Such enhancements in sensitivity expand potential applications in human health and environmental monitoring.

Source: Sensors and Actuators Reports

DOI: 10.1016/j.snr.2025.100343

Authors: Mark S. Ferris, Anthony Adesso, Gary Zabow

Institutions: National Institute of Standards and Technology, University of Colorado Boulder

Language: English

Topic: Advanced Materials and Mechanics

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,430

Funders: U.S. Department of Commerce, National Institute of Standards and Technology