(Invited) 3D-Printed Bio-Inspired Electrophysiological Sensors
Authors: El-Atab Nazek , Alsharif Aljawharah 
Published: August 2024

Miniaturized bioinspired architectures used in diagnostic and therapeutic devices have garnered considerable attention due to their ability to deliver enhanced performance coupled with excellent biocompatibility, breathability, flexibility, and minimized side effects. This is particularly significant for applications involving neonates, infants, or individuals with atopic dermatitis [1], where traditional glue-based adhesives pose risks of skin contamination, injury, and interference with biosignal monitoring near wet wound areas or wet skin.

The imperative development of bioinspired, reusable, drainable, and contaminant-free transdermal patches, along with therapeutic systems or attachable devices featuring diagnostic sensing components, is crucial for patients necessitating specialized medical care. The rising demand for such adhesives is evident in their application for long-term diagnosis, therapy, or rehabilitation [2].

Taking inspiration from aquatic creatures, which have evolved two primary underwater attachment strategies—pressure-driven (suction attachment) and glue-like (bioadhesive secretions)—bioinspired suction-based adhesives with diverse multiscale architectures have been reported. These designs mimic the attachment behavior of octopi, tree frogs, beetles, leeches, snails, and geckos, demonstrating impressive mechanical enhancements and accurate biosignal monitoring capabilities [3-5]. However, the microfabrication processes described in existing literature are often complex, labor-intensive, and costly.

In response to this challenge, recent advancements in electrode and adhesive printing, particularly through three-dimensional (3D) printing, have gained favor among academics and researchers. 3D printing offers a viable alternative by providing high-quality signal measurements, optimal performance, cost-effectiveness, and customization. In this work, a simplified fabrication technique primarily based on Stereolithography (SLA) 3D printing is demonstrated. The technique aims to create a permeable skin patch featuring miniaturized octopus-like suckers, enhancing adhesion and facilitating precise biosignal monitoring across various skin conditions.

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2- S. Baik, J. Kim, H. J. Lee, T. H. Lee, and C. Pang, “Highly Adaptable and Biocompatible Octopus-Like Adhesive Patches with Meniscus-Controlled Unfoldable 3D Microtips for Underwater Surface and Hairy Skin,” Advanced Science, vol. 5, no. 8, Aug. 2018, doi: 10.1002/advs.201800100.

3- S. Chun et al., “Conductive and Stretchable Adhesive Electronics with Miniaturized Octopus-Like Suckers against Dry/Wet Skin for Biosignal Monitoring,” Adv Funct Mater, vol. 28, no. 52, Dec. 2018, doi: 10.1002/adfm.201805224.

4- D. W. Kim et al., “Highly Permeable Skin Patch with Conductive Hierarchical Architectures Inspired by Amphibians and Octopi for Omnidirectionally Enhanced Wet Adhesion,” Adv Funct Mater, vol. 29, no. 13, Mar. 2019, doi: 10.1002/adfm.201807614.

5- S. Baik, D. W. Kim, Y. Park, T. J. Lee, S. Ho Bhang, and C. Pang, “A wet-tolerant adhesive patch inspired by protuberances in suction cups of octopi,” Nature, vol. 546, no. 7658, pp. 396–400, Jun. 2017, doi: 10.1038/nature22382.