Blast Capsule: An Embedded Pressure Sensing System for Internal Blast Pressure Measurement

Abstract

The mechanisms of blast injury in air and water have not been fully elucidated. Understanding how a certain dose of blast energy leads to injury is essential to develop accurate and usable safe standoff distance guidance. Such guidance is important for those who work with and around explosives. This information can also be beneficial for environmental concerns, potentially mitigating blast injuries in marine and terrestrial animals. Improved technologies to accurately measure blast energy dosage and relate it to observed injury are needed. We demonstrate a functioning prototype of an ingestible capsule that measures the internal pressures that occur within an organism due to underwater or in-air blast exposure. The capsule has a form factor similar to devices used for capsule endoscopy. It was tested with pressure waves delivered by indirect Hopkinson bar impacts and small explosive blasting caps. The capsule effectively captured pressure wave signals and recorded peak pressures as close as 9% of a reference sensor's recorded signal. Throughout the testing process, the device also underwent design revision to further its effectiveness and reliability. The successful operation of this capsule is a first step toward more robust experiments that will better quantify the amount of blast energy that leads to an observed injury.