Ichikawa Kenta, Iitani Kenta, Kawase Gentaro, Toma Koji, Arakawa Takahiro, Dao Dzung Viet, Mitsubayashi Kohji
Department of Biomedical Devices and Instrumentation, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Tokyo 101-0062, Japan.
Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan.
Sensors (Basel). 2024 Feb 23;24(5):1436. doi: 10.3390/s24051436.
Salivary turbidity is a promising indicator for evaluating oral hygiene. This study proposed a wearable mouthguard-type sensor for continuous and unconstrained measurement of salivary turbidity. The sensor evaluated turbidity by measuring the light transmittance of saliva with an LED and a phototransistor sealed inside a double-layered mouthguard. The sensor was also embedded with a Bluetooth wireless module, enabling the wireless measurement of turbidity. The mouthguard materials (polyethylene terephthalate-glycol and ethylene-vinyl acetate) and the wavelength of the LED (405 nm) were experimentally determined to achieve high sensitivity in salivary turbidity measurement. The turbidity quantification characteristic of the proposed sensor was evaluated using a turbidity standard solution, and the sensor was capable of turbidity quantification over a wide dynamic range of 1-4000 FTU (formazine turbidity unit), including reported salivary turbidity (400-800 FTU). In vitro turbidity measurement using a saliva sample showed 553 FTU, which is equivalent to the same sample measured with a spectrophotometer (576 FTU). Moreover, in vivo experiments also showed results equivalent to that measured with a spectrophotometer, and wireless measurement of salivary turbidity was realized using the mouthguard-type sensor. Based on these results, the proposed mouthguard-type sensor has promising potential for the unconstrained continuous evaluation of oral hygiene.
唾液浊度是评估口腔卫生状况的一个有前景的指标。本研究提出了一种可穿戴式护齿型传感器，用于连续、不受约束地测量唾液浊度。该传感器通过测量密封在双层护齿内的发光二极管（LED）和光电晶体管对唾液的透光率来评估浊度。该传感器还嵌入了蓝牙无线模块，能够对浊度进行无线测量。通过实验确定了护齿材料（聚对苯二甲酸乙二醇酯二醇和乙烯-醋酸乙烯酯）以及LED的波长（405纳米），以在唾液浊度测量中实现高灵敏度。使用浊度标准溶液评估了所提出传感器的浊度定量特性，该传感器能够在1 - 4000福尔马肼浊度单位（FTU）的宽动态范围内进行浊度定量，包括已报道的唾液浊度（400 - 800 FTU）。使用唾液样本进行的体外浊度测量显示为553 FTU，这与用分光光度计测量的同一样本结果（576 FTU）相当。此外，体内实验也显示出与分光光度计测量结果相当的结果，并且使用护齿型传感器实现了唾液浊度的无线测量。基于这些结果，所提出的护齿型传感器在不受约束地连续评估口腔卫生方面具有广阔的应用潜力。
