Novel 3D printed probe for bioimpedance spectroscopic measurement of oral mucosa: design and testing with ex vivo porcine oral tissues

Abstract

Three-dimensional (3D) printing has a high potential in various biomedical applications. We hypothesize that 3D printing could be a viable option to construct novel bioimpedance spectroscopic (BIS) sensors suitable for electrochemical characterization of oral mucosal tissues. Previous BIS studies have relied on hand-made probes possessing significant limitations related to their single patient disposable use, large inter-probe differences, and weak reproducibility of measurement. There is also uncertainty related to the effect of varying loading pressure between the probe and biological tissue. Here, we introduce three differently sized rectangular shaped 3D printed probes and test those using a four-terminal measurement principle on various porcine oral tissue samples. We find that constructing a fully 3D printed probe is a challenging task, prone to issues relating to short-circuiting or electrochemical corrosion. However, our final prototype version, constructed with silver-coated copper electrodes, showed favorable characteristics in BIS experiments. All three differently sized probes were able to differentiate between different tissue types with excellent reproducibility. The effect of loading pressure was found to be almost negligible when using small- and medium-sized probes. However, further studies are needed to measure tissues with uneven surfaces, such as palatinum, and to avoid manual or (electro)chemical surface-finishing steps.