Blast-Induced Color Change in Photonic Crystals Corresponds with Brain Pathology

Abstract

A high incidence of blast exposure is a 21st century reality in counter-insurgency warfare. However, thresholds for closed-head blast-induced traumatic brain injury (bTBI) remain unknown. Moreover, without objective information about relative blast exposure, warfighters with bTBI may not receive appropriate medical care and may remain in harm's way. Accordingly, we have engineered a blast injury dosimeter (BID) using a photonic crystalline material that changes color following blast exposure. The photonic crystals are fabricated using SU-8 via multi-beam interference laser lithography. The final BID is similar in appearance to an array of small colored stickers that may be affixed to uniforms or helmets in multiple locations. Although durable under normal conditions, the photonic crystalline micro- and nano-structure are precisely altered by blast to create a color change. These BIDs were evaluated using a rat model of bTBI, for which blast shockwave exposure was generated via a compressed air-driven shock tube. With prototype BID arrays affixed to the animals, we found that BID color changes corresponded with subtle brain pathologies, including neuronal degeneration and reactive astrocytosis. These subtle changes were most notable in the dentate gyrus of the hippocampus, cerebral cortex, and cerebellum. These data demonstrate the feasibility of using a materials-based, power-free colorimetric BID as the first self-contained blast sensor calibrated to correspond with brain pathology.

25th Anniversary Article: Ordered Polymer Structures for the Engineering of Photons and Phonons

“…The microstructure undergoes various deformation modes resulting in a complex deformation pattern with strong gradients. The prototype blast injury dosimeter arrays were also affixed to animals and a correspondence found between the blast injury dosimeter color changes and brain pathologies, including neuronal degeneration and reactive astrocytosis . The power‐free colorimetric sensing motif may allow this type of blast injury dosimeter to be deployed for use by warfighters.…”

The Mechanics of Traumatic Brain Injury: A Review of What We Know and What We Need to Know for Reducing Its Societal Burden

“…Technology is already developed for detecting threshold blast overpressures in the field [234][235][236]. Acting as a sensor for deciding if a soldier warrants medical evaluation, this application is not designed as a precise recording technology.…”

Validation of a blast induced neurotrauma model using modified Reddy tube in rats: A pilot study

“…On the surface subdural, subarachnoid haemorrhages and parenchymal injuries to the cortex, cerebellum and medulla have been noted. 14 Microscopic evaluation findings are normal brain architecture, reactive gliosis, neuronal swelling, cytoplasmic vacuolation and degeneration, axonal damage either focal or diffuse. Presence of activation and proliferation of microglia, astrocytes and inflammation 1e14 days after injury has also been demonstrated.…”