An implantable microfluidic device for self-monitoring of intraocular pressure

Abstract

Glaucoma is the second most common cause of blindness in the world. It is a multifactorial disease with several risk factors, of which intraocular pressure (IOP) is a primary contributing factor. IOP measurements are used for glaucoma diagnosis and patient monitoring. IOP has wide diurnal fluctuation and is dependent on body posture, so the occasional measurements done by the eye care expert in the clinic can be misleading. Here we show that microfluidic principles can be used to develop an implantable sensor that has a limit of detection of 1 mm Hg, high sensitivity and excellent reproducibility. This device has a simple optical interface that enables IOP to be read with a smartphone camera. This sensor, with its ease of fabrication and simple design, as well as its allowance for IOP home monitoring, offers a promising approach for better care of patients with glaucoma.

Emerging flexible and wearable physical sensing platforms for healthcare and biomedical applications

“…Physical sensing platforms that detect and monitor the surroundings and communicate with the acquired physical data, such as pressure, shear, strain, torsion, temperature, and humidity, form the fundamental building blocks of a multitude of advanced applications, including wearable consumer electronics [1][2][3] , soft robotics [4][5][6] , smart medical prosthetics and electronic skins [7][8][9] , and real-time healthcare monitoring 10,11 . With increasing demand for these applications, there is a corresponding increase in the requirements and criteria for the development and effective implementation of such sensors.…”

“…As such, recent years have seen the advent of a particular class of physical sensing devices, that is, lightweight, flexible, and wearable physical sensors with distinct functionalities, notably with high degrees of deformability and conformability, long-term stability, increased sensitivity, and excellent optical transparency [12][13][14][15] . In general, these sensing devices are functionally optimized for particular platforms and applications and may be stand-alone, portable, wearable, or implantable 10,16 . Compelling evidence of the rapid development of flexible and wearable physical sensing platforms can be traced from the progressive increase in the total number of scientific publications specific to this field over the past several years.…”

Pressure sensor based on flexible photonic crystal membrane

“…This demonstrates that due to the imaging approach a correction for movement is possible and should be studied in detail for technology transfer towards application. The electronic sensor from N. Xue et al [2] has a theoretical detection limit lower than 1 mmHg and the microfluidic based sensor from I. E. Araci et al [4] has in average error of 0.5 mmHg in their measurements. We calculated an LOD of around 160 Pa or 1.2 mmHg for our PDMS membrane based sensor, which is higher but on the same order of magnitude.…”

“…Furthermore, they are not transparent and need to be placed far enough outside of the optical axis to not impair the patient. Other implantable devices without power supply have been suggested for camera read out [3,4], but due to their exclusively transparent nature their contrast for pressure indication is rather low. We previously demonstrated a pressure sensor based on pressing a flexible membrane against a rigid photonic crystal waveguide [5].…”

A microscale optical implant for continuous in vivo monitoring of intraocular pressure

“…Such large implants have damaged surrounding 1 tissues and led to medical complications 66,67 . Previously investigated optical sensing approaches include a fiber-tip-based interferometry for hydrostatic pressure sensing [68][69][70][71][72][73][74] , a visualidentification-based method applied to pressure-sensitive microfluidic or micromechanical structures 75,76 , and laser-excited fluorescence measurements for ICP and IOP monitoring 77,78 . These approaches are promising, and with more improvements in terms of miniaturization and readout techniques, they may become practical approaches for IOP monitoring.…”