Yu Hang, Zhang Xingguo, Zheng Hao, Li Dachao, Pu Zhihua
State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, China.
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing, China.
Int J Bioprint. 2023 Mar 29;9(4):722. doi: 10.18063/ijb.722. eCollection 2023.
104Flexible antennas, which can conform to the skin and transfer signals to terminals, are particularly useful for wearable electronics. Bending, which frequently occurs to flexible devices, significantly affects the performance of flexible antennas. Inkjet printing has been used as an additive manufacturing technology for fabricating flexible antenna in recent years. However, there is little research on the bending performance of inkjet printing antenna in both simulation and experiment. This paper proposes a bendable coplanar waveguide antenna with a small size of 30 × 30 × 0.05 mm by combining the advantages of fractal antenna and serpentine antenna, which realizes the ultra-wideband feature and avoids the problems of large dielectric layer thickness (greater than 1 mm) and large volume of traditional microstrip antenna at the same time. The structure of the antenna was optimized by simulation using the Ansys high-frequency structure simulator, and the antenna was fabricated on a flexible polyimide substrate by inkjet printing. The experimental characterization results show that the central frequency of the antenna is 2.5 GHz, the return loss is -32 dB, and the absolute bandwidth is 850 MHz, which is consistent with the simulation results. The results demonstrate that the antenna has anti-interference capability and can meet the ultra-wideband characteristics. When the traverse and longitudinal bending radius are greater than 30 mm and skin proximity greater than 1 mm, the resonance frequency offsets are mostly within 360 MHz, and return losses of the bendable antenna are within the -14 dB compared with the no bending condition. The results exhibit that the proposed inkjet-printed flexible antenna is bendable and promising for wearable applications.
104可贴合皮肤并将信号传输到终端的柔性天线，对于可穿戴电子产品尤为有用。柔性设备经常发生的弯曲会显著影响柔性天线的性能。近年来，喷墨印刷已被用作制造柔性天线的增材制造技术。然而，在模拟和实验方面，关于喷墨印刷天线弯曲性能的研究很少。本文结合分形天线和蛇形天线的优点，提出了一种尺寸为30×30×0.05 mm的小型可弯曲共面波导天线，该天线实现了超宽带特性，同时避免了传统微带天线介电层厚度大（大于1 mm）和体积大的问题。利用Ansys高频结构模拟器通过模拟对天线结构进行了优化，并通过喷墨印刷在柔性聚酰亚胺基板上制作了天线。实验表征结果表明，天线的中心频率为2.5 GHz，回波损耗为-32 dB，绝对带宽为850 MHz，与模拟结果一致。结果表明该天线具有抗干扰能力，能够满足超宽带特性。当横向和纵向弯曲半径大于30 mm且与皮肤的距离大于1 mm时，共振频率偏移大多在360 MHz以内，与未弯曲状态相比，可弯曲天线的回波损耗在-14 dB以内。结果表明，所提出的喷墨印刷柔性天线具有可弯曲性，在可穿戴应用方面具有广阔前景。
