Contact-Lens Biosensors

Abstract

Rapid diagnosis and screening of diseases have become increasingly important in predictive and preventive medicine as they improve patient treatment strategies and reduce cost as well as burden on our healthcare system. In this regard, wearable devices are emerging as effective and reliable point-of-care diagnostics that can allow users to monitor their health at home. These wrist-worn, head-mounted, smart-textile, or smart-patches devices can offer valuable information on the conditions of patients as a non-invasive form of monitoring. However, they are significantly limited in monitoring physiological signals and biomechanics, and, mostly, rely on the physical attributes. Recently, developed wearable devices utilize body fluids, such as sweat, saliva, or skin interstitial fluid, and electrochemical interactions to allow continuous physiological condition and disease monitoring for users. Among them, tear fluid has been widely utilized in the investigation of ocular diseases, diabetes, and even cancers, because of its easy accessibility, lower complexity, and minimal invasiveness. By determining the concentration change of analytes within the tear fluid, it would be possible to identify disease progression and allow patient-oriented therapies. Considering the emerging trend of tear-based biosensing technology, this review article aims to focus on an overview of the tear fluid as a detection medium for certain diseases, such as ocular disorders, diabetes, and cancer. In addition, the rise and application of minimally invasive detection and monitoring via integrated contact lens biosensors will also be addressed, in regards to their practicality and current developmental progress.

The Current Trends of Biosensors in Tissue Engineering

“…For example, tear-based biosensing technology has been used to generate contact-lens biosensors. Through the detection of tear, this biosensor could be used for continuous monitoring of diabetes [111]. This information shows that wearable biosensors with a potential as a non-invasive measurement method to directly obtain the health information from human by detecting sweat, saliva, tear, and other body fluids.…”

Lab on the eye: A review of tear-based wearable devices for medical use and health management

“…Currently, two types of contact lens-based sensors, optical and electrochemical biosensing, have been developed (29). The earliest optical sensors measured tear glucose by detecting the fluorescence of molecules that competitively bind with glucose such as concanavalin A or phenylboronic acid derivatives (29).…”

“…Currently, two types of contact lens-based sensors, optical and electrochemical biosensing, have been developed (29). The earliest optical sensors measured tear glucose by detecting the fluorescence of molecules that competitively bind with glucose such as concanavalin A or phenylboronic acid derivatives (29). Several teams developed contact lenses embedded with fluorescent nanoparticles or boronic acid-containing fluorophores to obtain the glucose concentration by measuring the fluorescence intensity and resonance energy transfer.…”

Grand Challenges in Nanomaterial-Based Electrochemical Sensors

“…If the sensor is not stable or functional in real samples then it cannot be validated as a diagnostic tool. A wide variety of real samples are often used with electrochemical sensors, the most common ones being urine, blood serum, sweat, saliva, tear, and interstitial fluid (Li et al, 2017;Lipani et al, 2018;Tseng et al, 2018;de Castro et al, 2019;Idili et al, 2019;Karpova et al, 2019;Sempionatto et al, 2019;Azeredo et al, 2020;Baghelani et al, 2020). The matrix effect tends to negatively interfere with the detection of a specific analyte which lowers the recovery values and the sensitivity of the sensor.…”

“…Tear fluid has also recently gained significant interest because it has lower complexity with easy access for non-invasive sampling techniques. Tear fluid is often used to investigate the progression of ocular diseases and diabetes (Tseng et al, 2018;Sempionatto et al, 2019). Some disadvantages with tear fluid include that the pH can vary, the sample volume is low and the tears from emotion and irritation may differ in composition (Tseng et al, 2018;Sempionatto et al, 2019).…”