Abstract
The human body is a complex system with many functions, and researchers are designing sensors to be placed within the body to monitor these functions in real-time with minimal invasiveness by using wireless power and communication methods. Ultrasound is a promising new method for wireless sensors, as it has low signal attenuation in tissue and can deliver more power for the same sized device. When testing ultrasonic devices, an alternative to human tissue is typically used, and common substitutes include animal tissue, castor oil, or water. The drawback of using animal tissue is that its properties change with time due to drying and decay. Water and castor oil properties are similar to average tissue layer properties, but not the individual layers. Although they have predictable and reliable properties, they do not mimic complex tissue anatomy well, and as they are homogenous, the reflections and refractions of ultrasound that occur in real life between tissue types do not occur. New gelatin products have emerged as promising materials for in vitro ultrasonic testing, because their properties can be chosen to mimic specific tissue layers with appropriate thicknesses. The purpose of this study was to validate techniques for the layering of gelatins, that mimic human tissue, for creating easily variable and repeatable heterogenous benchtop materials. This study used Humimic Medical Gelatin #0, a gelatin that mimics the properties of human fat. The slabs were 125 × 125 mm with thicknesses of 10, 20, and 50 mm. The ultrasound transducers were 1 MHz lead zirconate titanate discs, and a signal generator was used to drive them. Voltages across the transmission transducer and “implanted” transducer were recorded with and without water and with acoustic gel used as coupling agents between the slabs. Results demonstrated that gelatin can be a suitable material for ultrasonic device testing but must be used in conjunction with water, as a coupling agent, on the transducer-gelatin boundary to get accurate and repeatable results between test setups.
