A system (800, 900) for identifying one or more changes in a biomarker sensitive hydrogel (806, 808) based on changes in concentration of one or more biomarkers, the biomarker sensitive hydrogel being positioned within an in vivo environment (810, 910), the system comprising: a biomarker sensitive hydrogel arranged in an array of acoustic resonators, the biomarker sensitive hydrogel being positioned within the in vivo environment and configured to dimensionally change, and thereby cause a volumetric change in the array of acoustic resonators, in response to interaction with one or more predefined biomarkers; an ultrasound transducer (802, 902) for locating the biomarker sensitive hydrogel within the in vivo environment and for identifying one or more characteristics of the biomarker sensitive hydrogel, including resonant frequencies of the array of acoustic resonators; a computer system in electrical communication with the ultrasound transducer, the computer system having one or more processors and being configured to: receive, from the ultrasound transducer, the one or more characteristics of the biomarker sensitive hydrogel, including a resonant frequency of the array of acoustic resonators; determine, at the one or more processors, one or more dimensional changes of the biomarker sensitive hydrogel, including a volumetric change in the array of acoustic resonators, based on the received one or more characteristics of the biomarker sensitive hydrogel; and determine concentration of the one or more biomarkers based on the one or more dimensional changes of the biomarker sensitive hydrogel. a biomarker sensitive hydrogel arranged in an array of acoustic resonators, the biomarker sensitive hydrogel being positioned within the in vivo environment and configured to dimensionally change, and thereby cause a volumetric change in the array of acoustic resonators, in response to interaction with one or more predefined biomarkers; an ultrasound transducer (802, 902) for locating the biomarker sensitive hydrogel within the in vivo environment and for identifying one or more characteristics of the biomarker sensitive hydrogel, including resonant frequencies of the array of acoustic resonators; a computer system in electrical communication with the ultrasound transducer, the computer system having one or more processors and being configured to: receive, from the ultrasound transducer, the one or more characteristics of the biomarker sensitive hydrogel, including a resonant frequency of the array of acoustic resonators; determine, at the one or more processors, one or more dimensional changes of the biomarker sensitive hydrogel, including a volumetric change in the array of acoustic resonators, based on the received one or more characteristics of the biomarker sensitive hydrogel; and determine concentration of the one or more biomarkers based on the one or more dimensional changes of the biomarker sensitive hydrogel. receive, from the ultrasound transducer, the one or more characteristics of the biomarker sensitive hydrogel, including a resonant frequency of the array of acoustic resonators; determine, at the one or more processors, one or more dimensional changes of the biomarker sensitive hydrogel, including a volumetric change in the array of acoustic resonators, based on the received one or more characteristics of the biomarker sensitive hydrogel; and determine concentration of the one or more biomarkers based on the one or more dimensional changes of the biomarker sensitive hydrogel.