We report an innovative, wearable, multiscale diffuse speckle contrast flowmetry (DSCF) probe for continuous transcranial imaging of cerebral blood flow (CBF) in animal s. Significant reductions in CBF during transient ligation of bilateral common carotid arteries were detected by DSCF (-35±13% in two mice and -59% in a piglet), meeting clinical expectations. Results from DSCF and an established CBF measurement device, diffuse correlation spectroscopy, were consistent and significantly correlated. With further optimization and validation in animals and humans, we expect to ultimately offer a unique, noninvasive, low-cost, and fast brain imaging tool for basic neuroscience research and clinical applications.

The HEMOCOVID-19 clinical trial, carried out in 10 hospitals from 5 countries, aims to non-invasively assess, through continuous-wave near-infrared spectroscopy (CW-NIRS), the microvascular and endothelial health in COVID-19 patients admitted to intensive care. We achieve this by performing a vascular occlusion test on the forearm muscle while continuously measuring local tissue oxygen saturation and hemoglobin concentration. We found significant alterations in systemic microcirculation of COVID-19 patients with respect to healthy subjects (i.e. slower deoxygenation during the ischemia and reoxygenation after releasing the cuff, and lower hyperemic response). In addition, we found that, within the group of COVID-19 patients, the systemic microcirculation alterations correlate with severity of pulmonary disease.

We present a wireless, wearable device to measure transcutaneous partial oxygen pressure (tcpO2) non-invasively. The device, tuned to physiological range pO2, detects changes in phosphorescence lifetime and intensity of ultra-bright metalloporphyrins embedded within breathable films.  We have implemented machine learning algorithms to improve the accuracy of the measurements against changes in temperature, photobleaching, inter-device/film variations, etc. Our first in human measurements reveal the devices are able to detect quick and subtle changes in tcpO2 due to local and systemic changes in blood flow of skin or deeper muscle tissue. Models to extract tissue oxygenation and oxygen consumption rate are explored.

Total hemoglobin concentration [total-Hb] and reduced scattering coefficient (µs’) measured using near-infrared time-resolved spectroscopy in supraclavicular regions (parameters used to evaluate brown adipose tissue density (BAT-d)) were compared between children and adults. This study included 217 children (114 girls and 103 boys; 2.1 ± 1.6 (mean ± SD) years) and 139 adults (103 females and 36 males; 37.1 ± 5.8 years). Parameters for BAT-d values in the supraclavicular region were significantly higher in children ([total-Hb], 86.9 ± 21.5 µM: µs’, 11.2 ± 1.6 cm-1) than in adults ([total-Hb], 62.7 ± 21.7 µM: µs’, 7.5 ± 1.2 cm-1).

We present an update on our high optode-density continuous-wave (CW) wearable diffuse optical device for the investigation of hemodynamic responses of locally advanced breast tumors during neoadjuvant chemotherapy (NAC). The device consists of a rigid-flex substrate with 32 LEDs at two wavelengths and 16 detectors. Measurements on spatially-complex flow phantoms have validated the ability to reconstruct temporal spatial absorption contrast. Preliminary results from a healthy volunteer study (N=4 volunteers) indicate that paced breathing hemodynamics can be quantified in healthy subjects, and initial clinical measurements (N=3) suggest that these hemodynamics may reveal strong tumor contrast in some instances.

Neuroimaging studies struggle from inter- and intra-subject variability of collected data. To overcome these barriers to statistical significance, researchers are pursuing naturalistic neuroimaging to increase the statistical power of their investigations. Although numerous devices have become available for prefrontal cortex imaging, fNIRS systems continue to struggle with significant weight (>200g) and dependence on experts for setup. Our group has developed an ergonomic fNIRS headset and an accompanying Android augmented reality (AR) app for system setup by lay users. The combination of low-cost technology with user-friendly guidance for accurate setup will enable new studies in naturalistic conditions.

Wearable systems can evaluate a subject’s gait without the need to meet a therapist. Some of these wearables are in the form of smartphone built-in sensors. Gait characteristics give us a knowledge of health status in individuals with movement disorders. In this study, we designed a gyroscope-based smartphone application for quantifying gait parameters through a built-in smartphone sensor. This method uses a custom created algorithm for measuring a person’s manner of walking. The outcome is an inexpensive application for tracking the prognosis of the disease and monitoring patient recovery that allows a point-of-care at-home monitoring of patients with limb problems.

The aim of this study was to clarify exercise-induced vasodilation by comparing the changes in muscle oxygenation during constant-work exercise (CWE) between untrained and endurance-trained individuals using time-resolved near-infrared spectroscopy (TR-NIRS). Ten healthy young untrained and 9 endurance-trained individuals performed CWE at moderate and high intensities each for 6 minutes. Muscle oxy/deoxygenation in the vastus lateralis was continuously monitored by TR-NIRS. Our results have demonstrated that endurance-trained individuals with high aerobic capacities showed increased muscle oxygenation during CWE, leading to higher exercise tolerance function. Thus, TR-NIRS can provide an optimal exercise training intensity for athletes to improve aerobic capacity.

We examined the seasonal variation of brown adipose tissue vascular density (BAT-d), which was estimated using total hemoglobin concentration in the supraclavicular region, in healthy subjects (9 men and 10 women) from November 2016 to November 2017. Generally, BAT-d was significantly higher in winter than in summer for all subjects. Although monthly BAT-d was significantly different for a year, no statistically significant difference was found from November to April. In conclusion, there was a seasonal variation of BAT-d from summer to winter and a lack of variation during late fall to the middle of spring among healthy subjects.

The development of a real-time, non-invasive method for assessing hydration status is urgently needed in many communities such as the military and high-performance athletes. A probe-based spatially offset Raman spectroscopy system has been developed to accomplish this goal. Raman spectra, including the fingerprint and high wavenumber regions, have been collected from various tissue depths and superficial anatomical locations from collegiate athletes undergoing strength and conditioning regimens. Urine was collected alongside spectroscopy measurements to compare spectral information to urine specific gravity, a clinically relevant hydration metric. Water dynamics shown in spectral features are used to quantify hydration change during exercise regimens.

We investigated the changes in the amount of brown adipose tissue (BAT) and the relationship between BAT and plasma branched-chain amino acids (BCAA) produced during strength training. Participants were randomly assigned to the workout (WO, n=9) or control (CT, n=9) groups. The plasma AA levels and the BAT density (BAT-d) in the supraclavicular region were assessed. The increase in BAT-d was comparable between the groups, but a significant inverse correlation was noted between the increase in BAT-d and BCAA in the WO group. Thus, BAT may modulate BCAA usage without changes in the amount of BAT by strength training.

A non-invasive, wearable Near Infrared Spectroscopy (NIRS) device was designed to measure in-vivo placental oxygenation. The device was used in a preliminary study in 12 healthy, singleton, pregnant volunteers at week 33.3±3.6 pregnancy. At postpartum, the placentas from 10 patients were then sent to a pathology lab, where five of them were found to have lesions. Placentas with lesions have significantly lower oxygenation levels (68.7% ± 5.6%) than the ones without lesions (74.2% ± 5.8%). This wearable NIRS device can be a potential point-of-care device to non-invasively check the lesion status of a placenta antepartum.