Medical tapes often hold critical devices to the skin so having high adhesion for the lifespan of this product is of great importance. However, the removal process is challenging for caregivers and patients alike, often a painful process that can cause medical adhesive-related skin injury (MARSI). By using an industrial thermally sensitive tape, a surrogate photosensitive tape was developed that switched from the equivalent of high-adhesion medical tape to low-adhesion medical tape. This resulted in an 86% reduction in the average peel strength when heated from 45 to 55 °C using a custom test apparatus. To photo-release the prototype tape (PT), a near-infrared (NIR) absorbing layer was painted on the visibly clear thermal-sensitive tape and an NIR optical wand using 15-LEDs (940 nm) with thermal feedback control was designed and tested. Preliminary performance of photo-to-thermal conversion was numerically modeled with transient results matching experimental measurements with 96.8% correspondence. Using the verified energy conversion model of the surrogate photosensitive tape, a new NIR optical wand was designed for rapid and noncontact release of a future medical tape at 10 deg lower than the release temperature (RTemp) of the custom adhesive, called UnTape. Numerical simulations compared to the thermal skin pain threshold of 45 °C predicts photo-release within 1.1 s of NIR exposure (85.5% absorption in PT at < 1.3 W/cm2). The unique properties of the multifunctional UnTape system (tape and portable NIR wand) may allow even stronger skin adhesion for critical medical devices while concurrently reducing the risk of MARSI upon photo release and easy removal.

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Chemical fixation is the slowest and often the most uncontrolled step in the multi-step process of preparing tissue for histopathology. In order to reduce the time from taking a core needle biopsy to making a diagnosis, a new approach is proposed that optically monitors the common formalin fixation process. A low-cost and highly-sensitive laser speckle imaging technique is developed to measure shear wave velocity in a biospecimen as small as 0.5 mm in thickness submerged in millifluidic channels. Shear wave velocity, which is the indicator of tissue mechanical property and induced by piezoelectric-actuation, was monitored using gelatin phantom and chicken breast during fixation, as well as post-fixed liver and colon tissues from human. Fixation levels in terms of shear wave velocity increased by approximately 271.0% and 130.8% in gelatin phantom and chicken breast, respectively, before reaching the plateaus at 10.91 m/s and 7.88 m/s. Within these small specimens, the plateaus levels and times varied with location of measurement, and between gelatin and chicken breast. This optical-based approach demonstrates the feasibility of fine-tuning preanalytical variables, such as fixation time, for a rapid and accurate histopathological evaluation; provides a quality metric during the tissue preparation protocol performed in most pathology labs; and introduces the millifluidic chamber that can be engineered to be a future disposable device that automates biopsy processing and imaging.

In this study, our collaborative research group explored the possibility of incorporating ultrasound elastography technology with a microfluidic device that is designed to prepare fine needle core biopsies (CBs; L=0.5–2.0 cm, D=0.4–1.2 mm) for pancreatic cancer diagnosis. For the first time, elastographic techniques were employed to measure shear wave velocity in fresh (3.7 m/s) and formalin-fixed (14.7 m/s) pancreatic CBs. Shear wave velocity did not vary whether fixed specimens were free on a microscope slide, or constrained within glass microfluidic channels: 11.5±1.9 v. 11.8±2.1 m/s. 4% agarose inclusions were also embedded within 1% agarose hydrogels to simulate cysts, neoplastic, or necrotic tissue within CBs. Inclusions were successfully visualized and measured using optical coherence elastography. These preliminary experiments demonstrate in a rudimentary fashion that elastographic measurements of pancreatic CBs may be incorporated with our microfluidic device. The rapid mapping of CB stiffness may provide qualitative spatial information for pathologists to determine a more accurate diagnosis for patients.