Electrospinning Equipment: A Liquid Diode-based Smart Bandage with Ultrasensitive pH Sensing Ability for Chronic Wound Management

Impaired healing ability of chronic wounds seriously affects patients' quality of life. Globally, over 40 million people are troubled by it, bringing a heavy economic burden. In recent years, wound dressings and bandages have developed rapidly. For example, hydrogel dressings with controlled drug release functions, wearable dressings that can provide electrical stimulation, and dressings using technologies such as antibiotics and photothermal therapy have certain effects on wound treatment, but they also have limitations. Most dressings cannot clean and drain wound exudate, resulting in exudate accumulation and hindering wound healing. Although self-pumping dressings can drain, they lack sensing modules and it is difficult to assess the wound healing status. In addition, existing dressings that can monitor wound pH cannot dynamically sense pH changes. Therefore, it is of great research significance to develop a smart bandage that can dynamically reflect the wound status and continuously drain exudate. Electrospinning machine is used in the production of related materials for this study. A team led by Wang Han from the Department of Biomedical Engineering at Tsinghua University published relevant research results. The results were published in the journal Microsystems & Nanoengineering under the title "Chronic wound management: a liquid diode - based smart bandage with ultrasensitive pH sensing ability". The team developed a smart bandage integrating a biocompatible liquid diode membrane and an ultrasensitive 3D polyaniline network (M - PANI)-based pH biosensor, successfully achieving unidirectional drainage of wound exudate and dynamic monitoring of the wound pH environment. This achievement provides a new solution for chronic wound management, is expected to promote the development of wound care technology, and offers an innovative approach for home - based wound management.

In this study, a bilayer membrane structure was formed by combining an ultra - hydrophilic polyether sulfone (PES) membrane with a hydrophobic thermoplastic polyurethane (TPU) membrane with the help of electrospinning device to construct a liquid diode with asymmetric wettability. Here, electrospinning device played a crucial role. A three - electrode system was screen - printed on the PES membrane, and electrospinning was performed on the TPU membrane to integrate the ultrasensitive 3D polyaniline network (M - PANI)-based pH biosensor into the liquid diode. Finally, M - PANI was immobilized on carbon fiber paper to form the sensing part of the smart bandage (see Figure 1d).

This smart bandage integrates a biocompatible liquid diode membrane and an ultrasensitive 3D polyaniline network (M - PANI)-based pH biosensor. The liquid diode membrane can achieve unidirectional drainage of wound exudate, prevent external liquid from flowing back, and keep the wound clean and dry. The M - PANI - based pH biosensor can dynamically sense the wound pH environment. As shown in Figure 1a, the smart bandage consists of a bilayer membrane, an integrated screen - printed carbon electrode, and a portable electrochemical workstation. During operation, wound exudate contacts the sensor through the liquid diode to achieve relevant functions.

The M - PANI - based pH biosensor has a high sensitivity of 61.5 mV/pH and a wide detection range from pH 4.0 to 10.0, covering the pH ranges of normal (pH 4.5 - 5.0) and infected wounds (pH 7.0 - 9.0). The performance can be seen from the open - circuit potential - time (OCPT) curves and linear fitting in Figure 2a - c. Corresponding to PBS solutions with different pH values, the sensor shows a good linear relationship (refer to Figure 5).

The sensing module has excellent stability. After 48 - hour dynamic testing and 28 - day storage, the detected signal only decreased by 4.8%. It also has high repeatability, with a relative standard deviation (RSD) between devices of 3.1%. Figure 2d shows the changes in OCPT responses at different times during the 28 - day storage period, reflecting stability. Figures 5g and h show the RSD obtained from testing multiple M - PANI/SPCEs in a 0.5M H2SO4 solution, reflecting repeatability.

To evaluate the practicality of the smart bandage, the research used simulated skin and rats for testing. In the rat experiment, a comparison was made between using the smart bandage and traditional gauze on circular full - thickness skin wounds (0.8 cm in diameter). The results showed that the smart bandage could reduce exudate accumulation and dressing adhesion, and accelerate wound healing. Figures 7d and e show the changes in wound area during the healing process, with a higher recovery rate in the smart - bandage group. Figure 7f shows through tissue staining that the smart bandage does not interfere with the repair of the dermal layer and promotes neovascularization, reflecting its great potential for clinical applications.

In conclusion, this study successfully developed a liquid-diode-based smart bandage via electrospinning machine that integrates a biocompatible liquid diode membrane and an ultrasensitive 3D polyaniline network pH biosensor, achieving unidirectional drainage of wound exudate and dynamic monitoring of the pH environment. Its sensor has excellent performance and shows great potential for clinical applications in simulated skin and rat experiments. This smart bandage not only provides an innovative method for chronic wound management, meets the needs of advanced wound care, and promotes the development of the wound care field, but also helps to reduce patients' pain and medical costs. Moreover, its components have potential for expansion in other fields, which is of great significance for personalized health management and precision medicine.

Article source: https://doi.org/10.1038/s41378-024-00801-6