Development of a Smartphone-Based Optical Device to Measure Hemoglobin Concentration Changes for Remote Monitoring of Wounds

Abstract

Telemedicine (TM) can revolutionize the impact of diabetic wound care management, along with tools for remote patient monitoring (RPM). There are no low-cost mobile RPM devices for TM technology to provide comprehensive (visual and physiological) clinical assessments. Here, a novel low-cost smartphone-based optical imaging device has been developed to provide physiological measurements of tissues in terms of hemoglobin concentration maps. The device (SmartPhone Oxygenation Tool—SPOT) constitutes an add-on optical module, a smartphone, and a custom app to automate data acquisition while syncing a multi-wavelength near-infrared light-emitting diode (LED) light source (690, 810, 830 nm). The optimal imaging conditions of the SPOT device were determined from signal-to-noise maps. A standard vascular occlusion test was performed in three control subjects to observe changes in hemoglobin concentration maps between rest, occlusion, and release time points on the dorsal of the hand. Hemoglobin concentration maps were compared with and without applying an image de-noising algorithm, single value decomposition. Statistical analysis demonstrated that the hemoglobin concentrations changed significantly across the three-time stamps. Ongoing efforts are in imaging diabetic foot ulcers using the SPOT device to assess its potential as a smart health device for physiological monitoring of wounds remotely.

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“…Likewise, a study using the SmartPhone Oxygenation Tool (SPOT) for remote patient wound monitoring reported obtaining written consent from all study participants. Still, this SbS was also used in a controlled, clinical PoC setting, minimizing the personal privacy risk for the participant [5].…”

“…Smartphones are essentially handheld computers, and their software applications (i.e., Apps) can passively collect temporal, geographical, screen usage, and other information from an array of embedded sensors, including accelerometers, gyroscopes, barometers, proximity, and pressure sensors. Additionally, their powerful central processing units (CPUs) enable them to actively acquire data using their front-facing cameras [4], rearfacing cameras [5], ambient light sensors (ALS) [6], capacitive touch sensors [7], microphones, and geolocating sensors. See Supplementary Information (SI) Fig.…”

Smartphone oxygenation measuring device to differentiate low-risk stable and chronic diabetic foot ulcers from high-risk complicated ulcers: a pilot study in India

“…This non-contact-based device consists of a smartphone clip-on and a data acquisition app. SPOT device was optimized across two NIR wavelengths (690 and 830 nm) for estimating changes in tissue oxygenation-based parameters 6 . In addition to syncing the source and detector, the app was developed to control the native smartphone camera and all its features.…”

“…Hemoglobin-based parameters in terms of ΔHbR and ΔHbO were estimated using a Modified Beer Lambert's Law (MBLL) relation and normalized across each other 6,7 . Oxygen saturation (StO2) was estimated as the ratio of ΔHbO and ΔHbT (ΔHbR+ΔHbO).…”

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“…An in-house smartphone-based optical imaging device (or SPOT -Smartphone oxygenation tool) capable of obtaining tissue oxygenation maps has been developed for wound monitoring (see Figure 1A). 3 Monitoring tissue oxygenation within and surrounding the wound could provide supplemental information for the physician to identify the wounds health. Melanin is a highly absorbing chromophore that can affect tissue oxygenation measurements if not accounted for during imaging studies.…”