Wearable device for remote monitoring of transcutaneous tissue oxygenation

Abstract

Wearable devices have found widespread applications in recent years as both medical devices as well as consumer electronics for sports and health tracking. A metric of health that is often overlooked in currently available technology is the direct measurement of molecular oxygen in living tissue, a key component in cellular energy production. Here, we report on the development of a wireless wearable prototype for transcutaneous oxygenation monitoring based on quantifying the oxygen-dependent phosphorescence of a metalloporphyrin embedded within a highly breathable oxygen sensing film. The device is completely self-contained, weighs under 30 grams, performs on-board signal analysis, and can communicate with computers or smartphones. The wearable measures tissue oxygenation at the skin surface by detecting the lifetime and intensity of phosphorescence, which undergoes quenching in the presence of oxygen. As well as being insensitive to motion artifacts, it offers robust and reliable measurements even in variable atmospheric conditions related to temperature and humidity. Preliminary in vivo testing in a porcine ischemia model shows that the wearable is highly sensitive to changes in tissue oxygenation in the physiological range upon inducing a decrease in limb perfusion.

Phosphorescent Microneedle Array for the Measurement of Oxygen Partial Pressure in Tissue

“…The wearable readout system was developed to monitor the oxygen partial pressure continuously on patients (Figure 1c). 37 Briefly, the readout system consists of a UV-emitting LED as an excitation source, a photodiode as a detector, and a thermocouple to assess the temperature. The system is capable of detecting emission intensity and phosphorescence lifetime and to convert this information into pO 2 values.…”

“…To test the compatibility of the MNA with an in-house developed optical wireless wearable readout system, an MNA was attached to the sensor head of the wearable device . The MNA was attached in a way that the LEDs and the photodiode of the sensor head faced the backplate of the MNA.…”

“…To test the compatibility of the MNA with an in-house developed optical wireless wearable readout system, an MNA was attached to the sensor head of the wearable device. 37 The MNA was attached in a way that the LEDs and the photodiode of the sensor head faced the backplate of the MNA. The MNA and the sensor head of the wearable device were applied on the skin sample along with an oxygen probe inside the skin and on its surface.…”

Quantitative Luminescence Photography of a Swellable Hydrogel Dressing with a Traffic‐Light Response to Oxygen

“…In this case, lifetime‐based techniques would be preferable, either alongside fluorescence lifetime imaging microscopy (FLIM) for 2D analysis of drugs in skin, [ 75,76 ] or using a wearable device which continuously monitors phosphorescence lifetime. [ 63,64,77 ] Incorporation of oxygen‐sensing materials into stretchable ionogels developed for wearable electronics [ 78 ] or nanofibrous aerogels with highly tunable mechanical properties [ 79 ] would also be advantageous for achieving continuous monitoring. Additionally while other formulations containing our Pt‐porphyrin core molecule have undergone preclinical [ 5,15 ] [ 54,55,80 ] and clinical [ 39 ] testing to verify correlations between pO 2 and stO 2 , long term biocompatibility must still be assessed preclinically prior to use in weeping wounds.…”

Wearable Ball-Impact Piezoelectric Multi-Converters for Low-Frequency Energy Harvesting from Human Motion

“…Their global market size has been valued at USD 32.63 billion in 2019 and is projected to further increase in the next years [ 1 ]. The interest in wearable electronic devices is due to the considerably wide number of possible applications, ranging from biomedical [ 2 , 3 , 4 , 5 ] to robotics [ 6 , 7 ] and from consumer [ 8 , 9 , 10 ] to industrial [ 11 , 12 ]. Wearable electronics have to fulfil some basic requirements, such as biocompatibility, light weight, and, in particular, low-energy consumption [ 13 ].…”