Skin‐Interfaced Deep‐Tissue Sensing Patch via Microneedle Waveguides

Abstract

keystone to creating temporally resolved therapeutics that can further reduce patient pains, prevent fatal events, and improve the wellbeing of individual life. One significant example with unmet needs for such technology focuses on peripheral artery disease (PAD), a family of disorder that causes stenosis or thrombus in the arteries/aorta of the limbs, compromises the physiological functions of the human extremities, and lead to symptoms including atypical leg pain and claudication. [1] Affecting the life quality of over 6.5 million Americans (5.8%, according to the 2000 Census population), [2] PAD harms the patient not only through its direct symptoms, but also by increasing the likelihood of myocardial infarction, ischemic stroke, and other cardiovascular diseases, which could further evolve into a prevalent factor of mobility impairment, mental issues, and mortality, especially in the elder. [3] Early warning signs correlated with PAD, which tend to be valuable in informing timely actions of preventive therapeutics before complications escalate, are, however, often neglected, or underappreciated, especially in low-resources settings. [4][5][6][7][8] Furthermore, the most commonly used indicator of PAD, ankle-brachial index (the ratio of the blood pressure measured at the ankle to the upper arm) has several major limitations, including: 1) long Continuous, real-time monitoring of biomarkers associated with local regions of the body can enhance both temporal and dimensional accuracy of proactive treatment to acute syndromes for critical illnesses, especially peripheral artery diseases. Conventional health monitors often face grand challenges in leveraging deep-tissue sensing capability with a safe and compatible biointerface.Optical-based noninvasive monitors may lack the ability to detect oximetry under subcutaneous fatty tissue due to the light scattering and absorption; implantables offer targeted sensing at depth, but may induce infection and inflammation. This report puts forward a wireless, wearable deep-tissue sensing patch by incorporating biocompatible microneedle waveguides at the sensing interface, to bypass the light extinction in epidermic and dermic tissue and enable the tracking of oximetry at muscular tissue. The sensing patch provides multiple physiological measurements at the sensing area, including tissue oximetry, pulse oximetry, heart pulsation, and respiratory activities with a wireless platform for uninterrupted data advertising and processing to enable real-time diagnostic analysis. The mechanical and thermal characterizations of the sensing patch with the microneedle waveguides validate the durable and safe operation at the skin interface. In vivo study with animal models of hindlimb ischemia demonstrates the high sensitivity and timely response of the sensing patch as muscle tissue hypoxia emerges.

Functional microneedles for wearable electronics

“…In addition, heart rate, pulse oximetry, and tissue oximetry could be measured by a microneedle waveguide-based biosensor. 82 When the subject was riding a bike, the recorded heart rate was significantly increased, with the pulse oximetry and tissue oximetry remained at ~98% and ~75%, respectively, indicating that pedaling was aerobic training. 82…”

“…82 When the subject was riding a bike, the recorded heart rate was significantly increased, with the pulse oximetry and tissue oximetry remained at ~98% and ~75%, respectively, indicating that pedaling was aerobic training. 82…”

“…Transparent microneedles can transmit light into deep tissue with minimal light attenuation (Figure 7A). 82 Using poly(lactic-co-glycolic acid) and polyvinyl alcohol as the microneedle materials, it was found that the penetration depths of red light (639 nm) and NIR light (950 nm) were enhanced with the assistance of these microneedle waveguides by 10.16 and 6.89 times, respectively (Figure 7B). By incorporating the microneedle waveguides with light-emitting diodes and photodiodes, the integrated sensor could efficiently measure multiple physiological signals, including pulse oximetry, tissue oximetry, pulse magnitude, and respiratory magnitude (Figure 7C).…”

“…By incorporating the microneedle waveguides with light-emitting diodes and photodiodes, the integrated sensor could efficiently measure multiple physiological signals, including pulse oximetry, tissue oximetry, pulse magnitude, and respiratory magnitude (Figure 7C). 82 In addition, since microneedles can easily access analytes in interstitial fluids without extraction or any excessive methods, it would be ideal to combine them with a field-effect transistor (FET) to build a household wearable biosensor. Such microneedle-based extended gate FET biosensors contained a FET transducer and a sensing part that was composed of a microneedle extended gate, a microneedle reference electrode, and a pair of silver nanowire electrodes (Figure 7D).…”

Battery-Free Optoelectronic Patch for Photodynamic and Light Therapies in Treating Bacteria-Infected Wounds

“…Flexible, stretchable, and biodegradable polymeric materials, such as synthetic polymers, hydrogels, and bioderived materials, have been explored in both in vitro and in vivo studies to overcome these challenges (12)(13)(14)(15)(16)(17)(18). Polymer microneedles (MNs) made from biocompatible and biodegradable materials like hyaluronic acid (HA) and polyvinyl alcohol (PVA) provide a minimally invasive means of transdermal drug delivery and light transmission to the deeper layers of the skin (19)(20)(21)(22)(23). In addition, light treatment is currently confined mainly to specialized healthcare settings due to the impracticality and high cost of home-based devices for widespread use.…”