A powerless optical microsensor for monitoring intraocular pressure with keratoprostheses

Ghannad-Rezaie, Mostafa; Gulari, Mayurachat Ning; Franco, Rafael de Melo; Chronis, Nikos

doi:10.1109/transducers.2013.6627365

Cited by 8 publications

(3 citation statements)

References 5 publications

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Lee

Park

et al. 2017

Microsyst Nanoeng

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Intraocular pressure (IOP) is a key clinical parameter in glaucoma management. However, despite the potential utility of daily measurements of IOP in the context of disease management, the necessary tools are currently lacking, and IOP is typically measured only a few times a year. Here we report on a microscale implantable sensor that could provide convenient, accurate, ondemand IOP monitoring in the home environment. When excited by broadband near-infrared (NIR) light from a tungsten bulb, the sensor's optical cavity reflects a pressure-dependent resonance signature that can be converted to IOP. NIR light is minimally absorbed by tissue and is not perceived visually. The sensor's nanodot-enhanced cavity allows for a 3-5 cm readout distance with an average accuracy of 0.29 mm Hg over the range of 0-40 mm Hg. Sensors were mounted onto intraocular lenses or silicone haptics and secured inside the anterior chamber in New Zealand white rabbits. Implanted sensors provided continuous in vivo tracking of short-term transient IOP elevations and provided continuous measurements of IOP for up to 4.5 months.

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Section: Introductionmentioning

confidence: 99%

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

Lee

Park

et al. 2017

Microsyst Nanoeng

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“…In addition, an increasing number of optics-based IOP and other biological pressure monitoring have been demonstrated based on flexible photonic crystal, 34 interferometry, [35][36][37][38][39][40][41][42] aberrometry, 43 microfluidic or micromechanical implants, 44,45 and laser-excited fluorescence. 46 To provide more accurate and frequent IOP monitoring and to improve treatment outcomes, researchers recently demonstrated implantable IOP sensors with remote optical readout in long-term in vivo studies. [47][48][49] The sensor is a hermetically sealed micro-optical cavity with a top surface made of a flexible, transparent Si 3 N 4 membrane and a bottom surface made of a mirror-like silicon substrate.…”

Section: Introductionmentioning

confidence: 99%

Effect of optical aberrations on intraocular pressure measurements using a microscale optical implant in ex vivo rabbit eyes

et al. 2018

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Elevated intraocular pressure (IOP) is the only modifiable major risk factor of glaucoma. Recently, accurate and continuous IOP monitoring has been demonstrated in vivo using an implantable sensor based on optical resonance with remote optical readout to improve patient outcomes. Here, we investigate the relationship between optical aberrations of ex vivo rabbit eyes and the performance of the IOP sensor using a custom-built setup integrated with a Shack-Hartmann sensor. The sensor readouts became less accurate as the aberrations increased in magnitude, but they remained within the clinically acceptable range. For root-mean-square wavefront errors of 0.10 to 0.94 μm, the accuracy and the signal-to-noise ratio were 0.58 ± 0.32 mm Hg and 15.57 ± 4.85 dB, respectively.

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“…Although several sensors have been developed to measure blood pressure in the ventricles [16]- [23], including RF powered telemetry [24]- [26], low power systems [27]- [31] and optical telemetry [23], [31], [32], none have been successful in measuring coronary arterial blood pressure. The main limitation is size.…”

Section: Introductionmentioning

confidence: 99%

An Implantable X-Ray-Based Blood Pressure Microsensor for Coronary In-Stent Restenosis Surveillance and Prevention

Gulari

Ghannad-Rezaie

Novelli

et al. 2015

J. Microelectromech. Syst.

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Coronary artery disease is a leading cause of mortality in the U.S. and percutaneous coronary intervention with stent placement is a common treatment. Stents often fail through coronary in-stent restenosis. Periodically monitoring restenosis could help alert the physician of any problems earlier, reduce myocardial reinfarctions, and improve outcomes. Currently, there are no inexpensive and noninvasive techniques to monitor stent patency. We describe an X-ray-addressable blood pressure (X-BP) microsensor. The X-BP has a column of radio-opaque liquid that changes its length with blood pressure. The X-BP allows for the noninvasive evaluation of the pressure drop across a stent and the fractional flow reserve (FFR) on radiographs. A FFR threshold of 0.75-0.8 is clinically established as the cutoff for the identification of hemodynamically significant stenosis that requires intervention. The X-BP membrane was modeled and the X-ray signal-to-noise ratio of different sensor dimensions was experimentally determined. Based on this data, optimal design parameters were selected. The sensor was prototyped and tested under microscope with radiographs and video fluoroscopy. The sensor has a potential dynamic range of 0-200 mmHg, and can reliably resolve the clinically important pressure drop of 20%-25% across the dynamic range for an FFR value of 0.8-0.75 or less. The X-BP also has a time constant <32 ms with no appreciable hysteresis. We believe this sensor can be used for periodic screening of coronary in-stent restenosis.[ 2014-0121]Index Terms-Pressure sensor, coronary in-stent restenosis, MEMS radiographs, x-rays, fractional flow reserve, myocardial perfusion.

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A powerless optical microsensor for monitoring intraocular pressure with keratoprostheses

Cited by 8 publications

References 5 publications

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

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

Effect of optical aberrations on intraocular pressure measurements using a microscale optical implant in ex vivo rabbit eyes

An Implantable X-Ray-Based Blood Pressure Microsensor for Coronary In-Stent Restenosis Surveillance and Prevention

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