Advanced Materials

Tunable Inverse Opal Hydrogel pH Sensors


  • This material is based upon work supported in part by the U.S. Department of Energy, Division of Materials Sciences under Award No. DEFG02-91ER45439, through the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign, and carried out in part in the Center for Microanalysis of Materials, University of Illinois, which is partially supported by the U.S. Department of Energy under grant DEFG02-91-ER45439. We thank an anonymous reviewer for pointing out several important points on hydrogel behavior.


The synthesis, swelling kinetics, and optical diffraction of inverse opal hydrogel sensors (see Figure) are demonstrated. Colloidal crystal templating is used to prepare methacrylate/acrylic acid (AA) copolymers that have an interconnected pore structure, allowing facile diffusion and a relatively rapid response. The system shows good mechanical stability and pH-dependent shifts in optical diffraction regulated by the AA concentration.