Micro-engineered poly(HEMA) hydrogel for wearable contact lens biosensing and other applications

Inventors

Khademhosseini, Alireza • Zhang, Shiming • Saha, Sourav • Dokmeci, Mehmet R. • Jiang, Lu

Assignees

CooperVision International Ltd • University of California San Diego UCSD

Abstract

Microchannels in hydrogels play an essential role in enabling a smart contact lens. A wearable contact lens is disclosed herein that uses microchannels and connected chambers located in poly-2-hydroxyethyl methacrylate (poly(HEMA)) hydrogel that is used in a commercial contact lens with three-dimensional (3D) printed mold. The corresponding capillary flow behaviors in these microchannels were investigated. Different capillary flow regimes were observed in these microchannels, depending on the hydration level of the hydrogel material. In particular, it was found that a peristaltic pressure could reinstate flow in a dehydrated microchannel, indicating the motion of eye-blinking may help tear flow in a microchannel-containing contact lens. Colorimetric pH and electrochemical Na+ sensing capabilities were demonstrated in these microchannels. Micro-engineered contact lenses formed using poly(HEMA) hydrogel can be used for various biomedical applications such as eye-care and wearable biosensing.

Core Innovation

The disclosed wearable contact lens includes a lens body with a base layer and a capping layer, where both the base layer and the capping layer comprise poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogel. The base layer has one or more microchannels formed therein and a plurality of chambers, with the one or more microchannels connected to the plurality of chambers, and the capping layer is bonded to the base layer and overlies the microchannels and the chambers.

The lens includes an inlet fluidically coupled to one of the plurality of chambers and an outlet fluidically coupled to one of the plurality of chambers. The microchannels and chambers enable capillary flow behavior that depends on hydrogel hydration level, including spontaneous Laplace pressure-driven capillary flow when fully hydrated, absent flow when fully dehydrated, and peristaltic-pressure-induced flow when mildly dehydrated, with external peristaltic pressure mimicking eye blinking reinstating flow.

The lens further integrates biosensing, including a colorimetric pH sensor in the microchannels or chambers and an electrochemical Na+ potentiometric sensor disposed in the microchannels or chambers. The pH sensing uses bromothymol blue, methyl red, or phenolphthalein, and the Na+ sensing uses a PEDOT:PSS-based electrode with a sodium ionophore. The document also describes possible tear-driven fluid transport and storage or release of therapeutic agents, drugs, or reagents associated with blinking-driven operation.

Claims Coverage

The consolidated content contains two independent claims. The main inventive features are the poly(HEMA) base-and-capping layered microchannel/chamber architecture with inlet and outlet, the integrated electrochemical sensing electrode comprising PEDOT:PSS with a sodium ionophore, and the lens-forming sequence using a mold with reverse features followed by plasma treatment or precursor reapplication prior to securing a poly(HEMA) capping layer.

Across the independent claims, the invention centers on a poly(HEMA) hydrogel contact lens architecture with bonded base and capping layers that define microchannels connected to chambers with inlet and outlet coupling, together with an electrochemical sensing electrode comprising PEDOT:PSS with a sodium ionophore. The second independent claim additionally defines a specific formation sequence using a mold with reverse microchannel features and plasma treatment or precursor reapplication prior to securing the poly(HEMA) capping layer.

Stated Advantages

Documented Applications

No documented applications found