Highly sensitive and chemically stable NH3 sensors based on an organic acid-sensitized cross-linked hydrogel for exhaled breath analysis
Highly sensitive and chemically stable NH3 sensors based on an organic acid-sensitized cross-linked hydrogel for exhaled breath analysis
复制标题
基于有机酸敏化交联水凝胶的高灵敏度且化学稳定的 NH3 传感器，用于呼气分析
DOI：
10.1016/j.bios.2021.113459
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发表时间：
2021-06-24
影响因子：
12.6
通讯作者：
Zhang, Tong
中科院分区：
文献类型：
--
作者：
Liu, Lichao;Fei, Teng;Zhang, Tong
由于人体呼出气体的高水分含量和复杂成分的干扰，具有良好选择性和稳定性的痕量氨（NH3）检测是呼出气体分析的一大挑战。羧基敏化水凝胶可以被水分激活，对NH3表现出显著的响应和优异的选择性。然而，水凝胶中羧基的高活性是一把双刃剑，导致在检测NH3时化学稳定性较差。本研究通过巯基光化学将有机酸嵌入交联聚乙二醇二丙烯酸酯（PEGDA）水凝胶中，形成稳定的水凝胶，用于在潮湿大气中检测NH3。结果表明，在高湿条件下（80% RH），最优传感器对不同干扰气体NH3表现出优异的选择性，对20 ppm NH3的NH3响应非常高（Za/Zg=6.20），在室温下的实际检测限极低（50 ppb）。此外，由于水凝胶复合材料的平衡含水量和酸基的酸解离常数适中，传感器表现出优异的化学稳定性。采用复阻抗谱（CIS）、石英晶体微天平（QCM）测量、傅里叶变换红外光谱（FT-IR）和x射线光电子能谱（XPS）研究了水激活NH3的传感机理。为了探索交联水凝胶传感器检测呼出NH3的应用前景，我们还进行了模拟呼出试验。
Due to interference by the high moisture content and complicated compositions of human exhaled breath, the trace-level detection of ammonia (NH3) with desirable selectivity and stability is a large challenge for exhaled breath analysis. Carboxyl-sensitized hydrogels can be activated by moisture to exhibit a significant response and excellent selectivity to NH3. However, the high activity of carboxyl groups in hydrogels is a double-edged sword, resulting in poor chemical stability during NH3 detection. Herein, organic acids were embedded into a crosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogel via thiol-ene photochemistry to form stable hydrogels for NH3 detection in a humid atmosphere. As a result, under high humidity conditions (80% RH), the optimal sensors exhibited superior selectivity to NH3 among various interfering gas species, a remarkably high NH3 response (Za/Zg=6.20) towards 20 ppm NH3, and an extremely low actual detection limit (50 ppb) at room temperature. Moreover, the sensors exhibited excellent chemical stability due to the moderate equilibrium water content of the hydrogel composites and acid dissociation constant of the acid groups. The moisture-activated NH3 sensing mechanism was thoroughly investigated by complex impedance spectroscopy (CIS), quartz crystal microbalance (QCM) measurements, Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). To explore the application prospects of cross-linked hydrogel sensors for detecting NH3 in exhaled breath, a simulated exhaled breath test was also performed.