Ultrathin and Robust Micro–Nano Composite Coating for Implantable Pressure Sensor Encapsulation

Abstract

Implantable pressure sensors enable more accurate disease diagnosis and real-time monitoring. Their widescale usage is dependent on a reliable encapsulation to protect them from corrosion of body fluids, yet not increasing their sizes or impairing their sensing functions during their lifespans. To realize the above requirements, an ultrathin, flexible, waterproof while robust micro–nano composite coating for encapsulation of an implantable pressure sensor is designed. The composite coating is composed of a nanolayer of silane-coupled molecules and a microlayer of parylene polymers. The mechanism and principle of the composite encapsulation coating with high adhesion are elucidated. Experimental results show that the error of the sensors after encapsulation is less than 2 mmHg, after working continuously for equivalently over 434 days in a simulated body fluid environment. The effects of the coating thickness on the waterproof time and the error of the sensor are also studied. The encapsulated sensor is implanted in an isolated porcine eye and a living rabbit eye, exhibiting excellent performances. Therefore, the micro–nano composite encapsulation coating would have an appealing application in micro–nano-device protections, especially for implantable biomedical devices.

Recent Advances in Two-Dimensional Nanomaterials for Healthcare Monitoring

“…Nanostructural design also enhances the biocompatibility of 2D nanomaterials; typically, smaller and thinner materials exhibit higher biocompatibility. , Biocompatible coatings or encapsulations function as protective barriers that prevent direct contact between 2D nanomaterials and biological components. − The biocompatibility of 2D nanomaterials is also improved by modifying their surface charge and introducing specific functional groups, which is verified by conducting extensive biological compatibility tests. − The integration of 2D materials into biodegradable composites, drug-delivery systems, and surface-patterning techniques facilitates their applicability in tissue engineering, drug delivery, and regenerative medicine. , …”

Recent Advances in Printing Technologies of Nanomaterials for Implantable Wireless Systems in Health Monitoring and Diagnosis

“…Rather than a topographical approach, a simple nano/micro coating was applied to a pressure sensor to improve interfacial adhesions and lifespan (Figure 4d). [ 86 ] The coating materials include a nanolayer of silane‐coupled molecules and a microlayer of parylene polymers. As shown in the SEM images (at 72 d after immersion in the simulated body fluid), the movable pressure sensor's surface with a two‐layer micro/nanocomposite coating (3.8 µm) showed a uniform, fine structure without surface defects.…”

“…Reproduced with permission. [ 86 ] Copyright 2020, American Chemical Society. e) Metal silicide alloy coating as an insoluble biofluid barrier and conductive electrical interface.…”

Flexible Strain Sensor Based on Copper/Graphene Composite Films

“…Furthermore, this design excellently resisted liquid interference, which has been proven effective in monitoring electronic eagles’ actions during artificial rainfall. On the contrary, Yao et al demonstrated the effectiveness of parylene as a microcomposite and nanocomposite water-resistant layer. Their investigations, which involved implanting sensors into the eyes of isolated pigs and living rabbits, underscored the superior performance of this material in protecting nanodevices, specifically those used for biomedical implants.…”