George W. Woodruff School of Mechanical Engineering, Center for Human-Centric Interfaces and Engineering, Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Department of Pediatrics, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06273, Korea.
Sensors (Basel). 2021 Feb 26;21(5):1642. doi: 10.3390/s21051642.
Saliva can be used for health monitoring with non-invasive wearable systems. Such devices, including electrochemical sensors, may provide a safe, fast, and cost-efficient way of detecting target ions. Although salivary ions are known to reflect those in blood, no available clinical device can detect essential ions directly from saliva. Here, we introduce an all-solid-state, flexible film sensor that allows highly accurate detection of sodium levels in saliva, comparable to those in blood. The wireless film sensor system can successfully measure sodium ions from a small volume of infants' saliva (<400 µL), demonstrating its potential as a continuous health monitor. This study includes the structural characterization and error analysis of a carbon/elastomer-based ion-selective electrode and a reference electrode to confirm the signal reliability. The sensor, composed of a pair of the electrodes, shows good sensitivity (58.9 mV/decade) and selectivity (log K = -2.68 for potassium), along with a broad detection range of 5 × 10 ≈ 1 M with a low detection limit of 4.27 × 10 M. The simultaneous comparison between the film sensor and a commercial electrochemical sensor demonstrates the accuracy of the flexible sensor and a positive correlation in saliva-to-blood sodium levels. Collectively, the presented study shows the potential of the wireless ion-selective sensor system for a non-invasive, early disease diagnosis with saliva.
唾液可用于通过非侵入式可穿戴系统进行健康监测。此类设备包括电化学传感器，可为检测目标离子提供安全、快速且经济高效的方法。虽然已知唾液中的离子可反映血液中的离子，但目前尚无临床可用的设备可直接从唾液中检测出必需离子。在这里，我们介绍了一种全固态、柔性薄膜传感器，可实现对唾液中钠离子的高度精确检测，其检测结果与血液中的钠离子相当。该无线薄膜传感器系统能够成功测量小体积 (<400 μL) 婴儿唾液中的钠离子，展示了其作为连续健康监测器的潜力。本研究包括对基于碳/弹性体的离子选择性电极和参比电极的结构特征和误差分析，以确认信号的可靠性。该传感器由一对电极组成，具有良好的灵敏度 (58.9 mV/decade) 和选择性 (log K = -2.68 对钾)，检测范围为 5 × 10 ≈ 1 M，检测限低至 4.27 × 10 M。薄膜传感器与商业电化学传感器的同步比较证明了柔性传感器的准确性以及唾液与血液中钠离子的正相关性。综上所述，本研究表明无线离子选择性传感器系统在通过唾液进行非侵入式、早期疾病诊断方面具有潜力。
