Self‐Adhesive Silicone Microstructures for the Treatment of Tympanic Membrane Perforations

Abstract

Inspired by the gecko foot, polymeric microstructures have demonstrated reliable dry adhesion to both stiff objects and sensitive surfaces such as skin. Microstructured silicone patches are proposed, herein, for the treatment of tympanic membrane perforations with the aim of serving as an alternative for current surgical procedures that require anesthesia and ear canal packing. Sylgard 184 PDMS micropillars of 20 μm in diameter and 60 μm in length are topped by a Soft Skin Adhesive (SSA) MG7‐1010 terminal layer, of about 25 μm thickness. The adhesion is evaluated by specially designed tack tests against explanted murine eardrums and, for comparison, against a rigid substrate. Functional effects are evaluated using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAE). The adhesion strength of the microstructure and unstructured controls to explanted murine tympanic membranes is comparable (typically 12 kPa), but the microstructured patches are easier to handle by the surgeon. For the first time, partial recovery of hearing performance is measured immediately after patch application. The novel patches adhere without the need for further fixation, removing the need for ear canal packing. The proposed material design holds great promise for improving clinical treatments of tympanic membrane perforations.

Film-Terminated Fibrillar Microstructures with Improved Adhesion on Skin-like Surfaces

“…This buckling event creates a “cushioning” or “overload protection”, which allows for dissipation of any extra applied force through the deformation of the subsurface microstructure . This effect will protect the counter surface against damage when applying a medical device on sensitive or injured tissue . The film-terminated design did not show loss of adhesion even after the fibrils were buckled, which is advantageous for reliable adhesion compared to microfibrils without film termination.…”

“…Dry adhesion is mediated by conformal contact, enhanced by a low effective elastic modulus, and Van der Waals (vdW) interactions, both of which contribute to useful adhesion even to rough surfaces. − For skin applications, a film-terminated design was proposed, which modifies the microfibril array by adding a continuous terminal layer made of softer material. This modified microstructure has shown enhanced adhesion by modulating the interfacial stresses and generating a crack trapping mechanism; the result is an interesting synergy between the subsurface microstructure and the soft, thin terminal layer. − The added layer also performs auxiliary functions: in wound dressings, it can aid in the closure of the wound; and in the treatment of eardrum perforations, it closes the fissure in the membrane, which is important to block pathogens from entering the middle ear during the treatment. , …”

“…19−22 The added layer also performs auxiliary functions: in wound dressings, it can aid in the closure of the wound; and in the treatment of eardrum perforations, it closes the fissure in the membrane, which is important to block pathogens from entering the middle ear during the treatment. 5,23 As the largest organ in humans, the skin presents an especially complex topography, which can vary over several orders of magnitude. The detailed structure depends on many factors, such as body location, age, and humidity.…”

“…Skin-attachable adhesives are experiencing rising demands in healthcare, where potential applications range from flexible and wearable electronics for monitoring and diagnosing biological signals − to therapeutic devices and wound dressings. , Biological surfaces and tissues are challenging counter surfaces to stick to, as surface roughness is one key factor for reduced adhesion . This is primarily due to the difficulty of achieving fully conformal contact, which decreases the real contact area and causes heterogeneous stress distributions at the interface .…”

Multiscale Synergistic Gecko-Inspired Adhesive for Stable Adhesion under Varying Preload and Surface Roughness

“…However, the wavelength of roughness needs to be higher than 4 times the fibril diameter to ensure sufficient contact, thereby constraining the GIA and promoting adhesive strength to rough surfaces. 31,32 In addition, hierarchical structures have been proposed to come into contact with the complex surfaces at different scales. Shao et al recently prepared a multiscale adhesive structure with a mechanically isolated energyabsorbing mesoscale backing layer and a mushroom-shapedmicroarray top layer, which exhibits adaptable adhesion to irregular surfaces on a millimeter scale and stable antivibration ability.…”