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 × 10⁻⁵ ≈ 1 M with a low detection limit of 4.27 × 10⁻⁵ 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.

中文翻译：

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唾液钠检测用柔性离子选择电极的研制

唾液可用于无创可穿戴系统的健康监测。这样的设备，包括电化学传感器，可以提供一种安全，快速且经济高效的方式来检测目标离子。尽管唾液离子可反映血液中的离子，但尚无可用的临床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，该传感器可以高度精确地检测唾液中的钠含量，与血液中的钠含量相当。无线薄膜传感器系统可以成功地测量少量婴儿唾液（<400 µL）中的钠离子，证明了其作为连续健康监测仪的潜力。这项研究包括碳/弹性体基离子选择电极和参比电极的结构表征和误差分析，以确认信号的可靠性。^-5 ≈1M的具有4.27×10的低检测限^-5 M.薄膜传感器和商业电化学传感器之间的同时比较表明了柔性传感器的准确度和唾液-血液钠水平呈正相关。总体而言，本研究显示了无线离子选择传感器系统在无创，唾液早期疾病诊断中的潜力。