Abstract: With the development of society, the conversion and utilization of micro energy has received increasing attention. Moisture-powered generation is a technology that converts the energy of moisture into electricity to meet energy demand and reduce dependence on traditional energy sources. The moisture-powered generator prepared by electrospinning has a large specific surface area and great porosity, resulting in a high voltage output and fast response rate during moisture-powered generation. However, the fine nanofibers of the membrane lack structural stability after absorbing moisture, which can lead to a drastic decline in device performance. The cycling performance of the nanofibrous membrane as a moisture-powered generator can be enhanced through appropriate crosslinking.
Therefore, in this paper, polyvinyl alcohol (PVA) and sodium alginate (SA) were used as raw materials, and different amounts of glutaraldehyde (GA) were added to cross-link and modify PVA and SA for the preparation of the spinning solution. GA crosslinking modified PVA/SA nanofiber film (G-PVA/SA) with certain water solubility resistance was prepared by electrospinning technology. The molecular structure, morphology, mechanical properties, moisture-powered generation properties and related applications of G-PVA/SA nanofiber films with different crosslinking degrees were tested and analyzed. The results show that GA can promote the effective cross-linking between PVA/SA molecules. With the increase of GA content, the degree of cross-linking between molecules increases, which leads to the increase of the fiber diameter, crystallinity and mechanical properties of the prepared G-PVA/SA nanofiber films. However, due to the decrease of hydrophilicity, the power generation performance of the moisture-powered generation device is slightly reduced. 0% G-PVA/SA nanofiber film (2 cm×2 cm) can produce 0.42 V voltage at high humidity (RH=85%), and 2% G-PVA/SA nanofiber film can produce 0.38 V voltage. After three cycles, 0% G-PVA/SA hygroscopic generation voltage decreases by 28.59%, while 2% G-PVA/SA nanofiber film hygroscopic generation voltage decreases by only 0.42%, and after 10 cycles, the open-circuit voltage remains at 0.36 V with a short-circuit current of 0.44 μA, which is only reduced by 6.5% and 4.4%, respectively. The cross-linking improves the water solubility resistance of G-PVA/SA nanofiber film and maintains the structural stability after moisture absorption.
In addition, by adjusting the distance between the finger and the device, various levels of output voltage can be monitored, which can be used to estimate the approximate distance between the human body and an object. Meanwhile, placing the device within a face mask allows for monitoring of different breathing intensities and frequencies through various waveforms of electrical output, thereby enabling the moisture-powered generator to be utilized in numerous real-life applications.

Key words: polyvinyl alcohol, sodium alginate, glutaraldehyde, crosslinking, electrospinning, moisture-powered generation

摘要： 为解决静电纺纳米纤维膜湿气发电器件吸湿后纤维易变形的问题，提高湿气发电器件的循环使用性能，采用戊二醛（GA）对聚乙烯醇（PVA）和海藻酸钠（SA）进行交联改性，通过静电纺丝技术制备了戊二醛改性聚乙烯醇/海藻酸钠（G-PVA/SA）纳米纤维膜，并将其应用于湿气发电。文章对G-PVA/SA纳米纤维膜的化学结构、微观形貌、结晶结构和力学性能进行了测试表征，研究了G-PVA/SA纳米纤维膜湿气发电机的发电性能和循环性能，并探索了其在监测传感方面的应用。结果表明：GA可使PVA/SA分子间发生交联，交联后的纺丝液粘度增加，所制备的G-PVA/SA纳米纤维膜纤维直径增大，结晶度上升，力学性能提高，但亲水性降低，其湿气发电性能略有降低。PVA、SA分子间的交联有效提高了纳米纤维的吸湿稳定性，保证了其湿气发电的循环稳定性。当溶液中加入GA的质量分数达2%时，所制备的纳米纤维膜在经10次循环后，湿气发电输出电压由0.38 V降至0.36 V（器件面积2 cm×2 cm），输出电压性能仅下降6.5%。基于其吸湿发电功能，该器件可有效监测湿气源（如人的手指等）的运动变化和人体呼吸的强度，在环境微能源采集、监测传感等方面表现出广阔的应用前景。

关键词: 聚乙烯醇, 海藻酸钠, 戊二醛, 交联, 静电纺丝, 湿气发电