School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China.
Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, China.
ACS Sens. 2023 Oct 27;8(10):3772-3780. doi: 10.1021/acssensors.3c01204. Epub 2023 Oct 16.
Continuous real-time monitoring of air quality is of great significance in the realms of environmental monitoring, personal safety, and healthcare. Recently, flexible gas sensors have gained great popularity for their potential to be integrated into various smart wearable electronics and display devices. However, the development of gas sensors with superior sensitivity, breathability, and stretchability remains a challenge. Here, a new high porosity thermoplastic polyurethane (HP-TPU) foam was reported for gas sensors, which exhibited large three-dimensional network structures and excellent mechanical properties. The HP-TPU foam was achieved by using a simple steam-induced method, which was suitable for mass production. The unique structure endowed this foam with 77.5% porosity, 260% strain ability, and 0.45 MPa Young's modulus, which improved 35, 31, and 80%, respectively, compared to previously reported traditional TPU foam (T-TPU) prepared by the drying method. In addition, the foam presented high gas permeability (312 g/m, 24 h) and excellent stability, and it remained undamaged even after 2000 cycles at 70% strain. The sensing material was coated on a PET flexible interdigital electrode and sandwiched between two HP-TPU foam layers for a gas sensitivity test. Due to the easy diffusion of gas between the pores and contact with the sensing materials, the HP-TPU foam exhibited a significant reduction of 85% in average response time and 46% in average recovery time, compared to the T-TPU foam. A wearable sensing device, comprising sensing, data processing, and wireless transmission modules, was successfully developed to enable outdoor testing and achieved a detection range at the ppb level. Finally, the cytotoxicity test results confirmed that this flexible gas sensor did not harm human health. These results proved that this HP-TPU foam was an ideal matrix for the flexible gas sensor, exhibiting great application potential in the fields of seamless human-machine integration.
空气质量的连续实时监测在环境监测、个人安全和医疗保健等领域具有重要意义。最近，由于其在各种智能可穿戴电子设备和显示设备中的应用潜力，柔性气体传感器受到了广泛关注。然而，开发具有更高灵敏度、透气性和拉伸性的气体传感器仍然是一个挑战。在这里，我们报道了一种新型高多孔热塑性聚氨酯（HP-TPU）泡沫，可用于气体传感器，该泡沫具有大的三维网络结构和优异的机械性能。HP-TPU 泡沫是通过使用简单的蒸汽诱导方法制备的，该方法适合大规模生产。独特的结构赋予了这种泡沫 77.5%的孔隙率、260%的应变能力和 0.45 MPa 的杨氏模量，分别比之前报道的通过干燥法制备的传统 TPU 泡沫（T-TPU）提高了 35%、31%和 80%。此外，该泡沫具有较高的透气性（312 g/m2，24 h）和出色的稳定性，即使在 70%应变下经过 2000 次循环也未损坏。将传感材料涂覆在 PET 柔性叉指电极上，并将其夹在两层 HP-TPU 泡沫层之间进行气体灵敏度测试。由于气体在孔之间易于扩散并与传感材料接触，因此与 T-TPU 泡沫相比，HP-TPU 泡沫的平均响应时间和平均恢复时间分别显著降低了 85%和 46%。成功开发了一种包含传感、数据处理和无线传输模块的可穿戴式传感装置，以实现户外测试，并达到了 ppb 级别的检测范围。最后，细胞毒性测试结果证实了这种柔性气体传感器对人体健康没有危害。这些结果证明，这种 HP-TPU 泡沫是一种理想的柔性气体传感器基质，在无缝人机集成领域具有巨大的应用潜力。
