A Rhodamine-B–Based Non-Contact Method for Spatial-Temporal Temperature Mapping Under Electromagnetic Exposure

The absorption of electromagnetic (EM) waves by the human body causes thermal changes that can disrupt cellular processes, damage tissues, and affect thermoregulatory functions. While computational simulations can model EM absorption and the resulting thermal changes within structurally complex tissues, the validation of these complex models requires experimental testbeds. However, traditional contact instruments such as thermocouples do not capture the full spatial-temporal changes in temperature and may introduce unwanted scattering of the incident EM waves. Thus, non-contact methods for measuring spatial-temporal thermal change within soft-tissue phantoms are necessary to validate computational predictions. Here, we demonstrate the use Rhodamine-B as a non-contact thermal probe to measure spatial-temporal temperature changes within aqueous solutions resulting from conductive heating (heating plate) and radiation heating (applied EM field) under white-light illumination. Further, we demonstrate the application of this non-contact temperature measurement to measure spatial-temporal heating and specific absorption rate of hydrogel phantoms with material properties that match those of human tissues and compare the results to computational models.