Impedance sensing device enables early detection of pressure ulcers in vivo

Abstract

When pressure is applied to a localized area of the body for an extended time, the resulting loss of blood flow and subsequent reperfusion to the tissue causes cell death and a pressure ulcer develops. Preventing pressure ulcers is challenging because the combination of pressure and time that results in tissue damage varies widely between patients, and the underlying damage is often severe by the time a surface wound becomes visible. Currently, no method exists to detect early tissue damage and enable intervention. Here we demonstrate a flexible, electronic device that non-invasively maps pressure-induced tissue damage, even when such damage cannot be visually observed. Using impedance spectroscopy across flexible electrode arrays in vivo on a rat model, we find that impedance is robustly correlated with tissue health across multiple animals and wound types. Our results demonstrate the feasibility of an automated, non-invasive 'smart bandage' for early detection of pressure ulcers.

Monitoring of Vital Signs with Flexible and Wearable Medical Devices

“…[ 101 ] Inkjet printing is well adept for depositing sparse, thin designs but becomes diffi cult for larger-sized features. [ 7,109,110 ] Gravure and fl exographic printing require higher viscosity inks for reliable printing. [ 101 ] While formulating high viscosity inks necessitates the use of highly soluble solutes, features as small as 5 µm can be reliably printed at speeds approaching one meter per second.…”

“…[ 2,3 ] Alternative materials, such as plastic and elastomeric substrates, used in these fl exible devices are conformal by nature, lightweight, and therefore offer better interface with the human skin and soft tissue. Many sensors also use electronic and optoelectronic materials that are fl exible by nature [4][5][6][7] while other approaches look into transferring small and thin conventional devices onto fl exible substrates. [ 8,9 ] Meanwhile, silicon-based electronics provide unparalleled performance in data processing and performance.…”

“…Additionally, fl exibility and a good fi t to the body can also improve signal quality and reduce noise from the measurement. [ 6,7 ] Medical devices are designed to diagnose, prevent, and treat disease. According to the Food and Drug Administration (FDA), a medical device should not achieve its purposes through chemical action within or on the body, and an agent which achieves its purpose through chemical action is termed as a drug.…”

Non-Invasive Assessment of Skin Barrier Properties: Investigating Emerging Tools for In Vitro and In Vivo Applications

“…The phase plot (Figure 3b) revealed a lower phase angle for Labskin compared to human skin. It has been suggested that a higher phase angle can be indicative of healthier cell membranes in the context of wound healing in vivo, however, this requires further investigation in HSEs to understand the implications of phase angle in studies in vitro [35,36].…”

Microfluidic platform for impedance characterization of endothelial cells under fluid shear stress.

“…The electrode material must have a low impedance and also be compatible with lithography and patterning techniques. Gold [40], [41], [77], [107], [109], [112], [121], [122], [126], [129]- [132], [136], [138], [139], [141], [147], [148], platinum [125], [134], [142], indium tin oxide (ITO) [118], [124], [140], [146], iridium [120], [128], [147], polysilicon [149], and carbon [150] have all been used as electrode materials. The electrode material can be sputtered, evaporated, deposited by PECVD, or even screen printed.…”