Hydrogel-Supported Optical-Microcavity Sensors

摘要

As the breadth of silicon-chip-based biomedical diagnostic (biosensors) and therapeutic (drug-delivery) technologies continues to expand, there exists a growing need to improve the biological-device interface for both in-vivo and ex-vivo applications. The biological-device interface sets operational constraints on the various mechanical, material, and preparatory aspects of how samples are collected, processed, and applied to a device, as well as on establishing requirements for device biocompatibility, tolerance towards biofouling, and the stability of immobilized bioreagents. Typically, silicon-chip-based devices (5-10 urn thick), including microfluidic microelectromechanical systems (MEMS) devices, are fabricated from and remain attached to the rigid bulk-silicon wafer support (~ 0.5-0.6 mm thick). This architecture may limit device function particularly for microfluidic porous structures, for which optimum function may depend on the directionality of flow through the device. Improving the biological-device interface could significantly advance the performance characteristics and versatility of chip-based devices while enabling new applications. For example, wound-care management could be advanced through the development of a "smart bandage", which is conceptualized as an optical device (2-10 urn thick) embedded in a flexible, therapeutic support matrix (e.g., polymeric gel). This architecture would improve the biological-device interface by enabling the "smart bandage" to be applied directly to a wound. A conformal contact could be made, thereby eliminating invasive sample collecting procedures. A support matrix could be selected to maintain the activity of bioreagents while enabling direct optical readout of the sensor response while contacting the wound. The sensor could be designed to change color, signaling the presence of types of bacteria, or if the wound required special care. Alternatively, the sensor could be used to monitor the release of biologically active substances concentrated within the porous matrix in a time-dependent fashion. Substances could be selected to support wound healing, including cytokines to promote immune function or growth factors to enhance cell proliferation, differentiation, and angiogenesis.'1'2'