Development and Validation of a Smartphone-Based Near-Infrared Optical Imaging Device to Measure Physiological Changes In-Vivo

Abstract

Smartphone-based technologies for medical imaging purposes are limited, especially when it involves the measurement of physiological information of the tissues. Herein, a smartphone-based near-infrared (NIR) imaging device was developed to measure physiological changes in tissues across a wide area and without contact. A custom attachment containing multiple multi-wavelength LED light sources (690, 800, and 840 nm; and <4 mW of optical power per LED), source driver, and optical filters and lenses was clipped onto a smartphone that served as the detector during data acquisition. The ability of the device to measure physiological changes was validated via occlusion studies on control subjects. Noise removal techniques using singular value decomposition algorithms effectively removed surface noise and distinctly differentiated the physiological changes in response to occlusion. In the long term, the developed smartphone-based NIR imaging device with capabilities to capture physiological changes will be a great low-cost alternative for clinicians and eventually for patients with chronic ulcers and bed sores, and/or in pre-screening for potential ulcers in diabetic subjects.

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

“…The first version of the SPOT device could obtain diffuse reflectance images at a single wavelength (690 nm) [ 21 ]. Herein, the SPOT device was modified to obtain diffuse reflectance images at multiple wavelengths (690, 810, 830 nm) and is further used to determine oxy- and deoxy-hemoglobin maps.…”

“…The SPOT device captured diffuse reflectance signals at multiple wavelengths (I λi (x, y)) for tissue oxygenation analysis. This analysis was achieved using a Modified Beer Lamberts Law (MBLL) approach at two wavelengths (690 and 830 nm) [ 21 , 22 ]. The major chromophore of interest was hemoglobin, and knowing the absorption properties are significantly different when hemoglobin is bound with oxygen (oxy-hemoglobin) compared to unbound or reduced hemoglobin (deoxy-hemoglobin), effective concentrations of each (∆HbO and ∆HbR) can be estimated.…”

“…Hence, tissue oxygenation is one of the key physiological parameters used to assess the effectiveness of the treatment approach in improving oxygen supply to DFUs (and thus enhances healing rates). A smartphone-based near-infrared (NIR) optical imaging device was recently developed [ 21 ] to measure physiological changes in tissues (in terms of diffuse reflectance signals) across a wide area and without contact. A NIR add-on optical module including a 690 nm light-emitting diode (LED), LED drivers, and diffuser sheet (for uniform illumination) was attached to the smartphone.…”

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

“…A smartphone-based optical imaging device (or SPOT, Smartphone oxygenation tool) has been developed to study changes in oxygenation using near-infrared (NIR) imaging technology 5 . This non-contact-based device consists of a smartphone clip-on and a data acquisition app.…”

Point‐of‐care optical devices in clinical imaging and screening: A review on the state of the art

“…In addition to its universal use in emergency medicine, pulse oximetry is also used as a congenital heart defect screening tool in newborns [16]. A non‐invasive smartphone‐based near‐infrared optical imaging device based on haemoglobin absorption variations has been advanced to measure physiological changes in tissues [17]. In addition, smartphone cameras were modified to include video microscopy that quantifies microfilariae parasites [18], wireless multiplexed diagnosis of infections [19], and quantitative colorimetric detection [20].…”