| Author: | Mo, Yongyi |
| Title: | Elastic adhesive bandage with adjustable mechanical and low-swelling properties as wearable bioelectronics |
| Advisors: | Zhao, Xin (ABCT) |
| Degree: | M.Phil. |
| Year: | 2026 |
| Department: | Department of Applied Biology and Chemical Technology |
| Pages: | xii, 80 pages : color illustrations |
| Language: | English |
| Abstract: | Skin adhesive bandages have drawn great attention as alternatives to conventional clinical closure techniques for healing and sealing damaged or injured wounds. However, current skin adhesives often exhibit compromised therapeutic efficacy due to excessive swelling, mismatched mechanical properties, and poor tissue adhesion. In addition to their traditional application in skin closure, adhesive bandages have been integrated into flexible electronic devices for accurate monitoring of human physiological signals. The secure attachment of flexible and wearable electronic devices requires a soft, elastic and adhesive substrate, thereby facilitating prompt, precise and accurate detection of physiological signals. Unfortunately, most modern adhesive bandage materials rely on van der Waals forces for adhesion, which can be easily disrupted by skin impurities, limiting their effectiveness for long-term and repeated usage. Therefore, the development of novel adhesive bandages is both critical and challenging, aiming to achieve strong and reliable tissue bonding for skin wound sealing as well as enhancing the accuracy and consistency of signal. In this study, we propose a soft, elastic, and adhesive bandage, which adhered firmly to skin tissue surfaces and exhibited excellent anti-swelling properties, for tight, fit-to-shape skin sealing and secure fixation of flexible electronic devices. The adhesive bandage, termed PLD-PS, was fabricated via a simple, one-step reaction by mixing the poly(lactide-co-propylene glycol) dimethacrylate (P₇L₂DMA, where 7 and 2 denote the unit lengths of polypropylene glycol (PPG) and lactide (LA), respectively), poly(lactide-co-propylene glycol) (P₇L₂) and a four-arm thiol pentaerythritol tetra(3-mercaptopropionate) (PTM) at room temperature. The photocrosslinkable and rigid P₇L₂DMA served as the structural framework, providing mechanical support and enabling a gentle fabrication process suitable for physiological environments. PTM, containing four thiol functional groups per molecule, reacted with the carbon-carbon double bonds (C=C) of P₇L₂DMA via a thiol-ene click reaction during photocrosslinking, and formed robust adhesion to tissues through disulfide (S-S) bond formation. P₇L₂ primarily modulated the mechanical properties of the adhesive by increasing inter-chain friction and energy dissipation through hydrogen bonds. The PLD-PS was further functionalized by programmable patterning with liquid metal gallium-indium eutectic, enabling the creation of a PLD-PS-based sensor, capable of accurately detecting electrocardiogram (ECG) signals both in vivo and in vitro. In this project, we first synthesized P₇L₂ and P₇L₂DMA, then optimized the concentrations of P₇L₂ and PTM (from 0 to 40 wt%) of the PLD-PS. Subsequently, we conducted a comprehensive evaluation of the mechanical, adhesive, swelling, in vitro sensing properties, and in vitro biocompatibility of PLD-PS. Mechanical properties were assessed by measuring the tensile modulus (ranged from 0.200 ± 0.073 MPa to 9.637 ± 0.260 MPa) and compressive modulus (ranged from 0.753 ± 0.084 MPa to 6.920 ± 0.740 MPa), demonstrating the compatibility of PLD-PS with various soft and hard tissues. The PLD-PS exhibited stable adhesive strength (approximately 60 kPa) and outstanding burst pressure (~1500 mmHg), ensuring conformal adhesion to skin. Furthermore, the PLD-PS displayed minimal swelling (~2% over 5 days) and limited degradation (less than 15% over 21 days), supporting its long-term stability. Additionally, we assessed the in vitro cytocompatibility of the PLD-PS with over 95% of cells maintaining viability and sustained proliferation after three days of co-incubation. What's more, PLD-PS demonstrated excellent hemocompatibility, with a hemolysis ratio of less than 1%. At last, the sensing properties of PLD-PS were further assessed, showing a broad sensing range from 0 to over 100% strain. After technological advancements, we fabricated a sandwich-structured PLD-PS-based sensor, encapsulating liquid metal within its middle layer. The newly formed sensor produced stable and reproducible electronic signals, enabling the monitoring of body joint movements (including wrist, elbow, and finger) and the transmission of Morse codes (such as "SOS" and "HELLO"). We envision that our proposed adhesive PLD-PS bandage exhibits the potential to facilitate rapid and accurate monitoring of ECG signals. Moreover, we anticipate that the PLD-PS adhesive bandage will inspire further research in the development of advanced substrates for flexible electronic devices. |
| Rights: | All rights reserved |
| Access: | open access |
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