Mg₂SiO₄ holds promise for its application in the microwave communication field due to its low dielectric constant and high Q×f value. However, its high negative τ_f and high sintering temperature limit its application in low-temperature co-fired ceramic (LTCC) devices. In this work, Li₂TiO₃ and CaTiO₃ were introduced to improve the τ_f, and LiF was chosen to decrease the sintering temperature. According to XRD patterns and SEM micrographs, the ceramic systems displayed a complex-phase structure, and the microstructure was densified when CaTiO₃ was added. All of the relative densities, dielectric constants, and Q×f values first increased and then decreased as the sintering temperature increased. The MLLC11.5 ceramics sintered at 800 °C could be obtained with the highest Q×f value of 54,581 GHz (at 8.06 GHz), ε_r of 14.13, and τ_f of + 5.81 ppm/°C. Furthermore, it was proven that the MLLC11.5 powders could be co-fired without any reaction with Ag powders at 800 °C, indicating its potential for LTCC application. The MLLC11.5 composition was used to prepare a GPS antenna and showed good prospects for its application in electronic communications.

Human cerebral oxygenation and hemodynamics can be estimated by cerebral oxygenation parameters. Functional near-infrared spectroscopy (fNIRS) can be used to measure the hemoglobin concentration index of brain tissue noninvasively and in real time. However, limited by cumbersome equipment, high price and uncomfortable wear, conventional fNIRS monitoring systems still cannot achieve continuous and long-term monitoring. In this work, a flexible and wearable long-term monitoring system is developed featured with cost efficiency, simple preparation and light weight (only 1.6 g), which consists of a pair of light-emitting diodes (LEDs) and a photodetector (PD). Triangular serpentine interconnectors are introduced to connect the functional elements, enabling the device to be stretched in multiple directions. The device can continuously work for 7 h and be subjected to 2000 cycles of bending loading, with less than 3% change in voltage value, 1.89% and 1.9% change in LED luminous power and 0.9% change in voltage value. Furthermore, the hand-gripping and breath-holding experiments show that the system can accurately measure the changes in hemoglobin concentration in accordance with the commercial device. The flexible fNIRS system presented here not only provides a simple preparation process but also offers new ideas for daily cerebral state monitoring and prolonged clinical monitoring.

胎心监测可有效反映胎儿在母体内的健康状态，为胎儿疾病诊断提供重要依据，连续精准的胎心监测对优生优育具有重要指导意义。目前胎心监测系统存在设备笨重、操作复杂、运动干扰等诸多问题，不便于随体长程连续监测。本文开发了一种柔性可穿戴式无线胎心电监测系统，通过5个柔性电极贴片构成多个测量通道和干扰消除通道，结合奇异值分解算法，提高胎心电测量精度。该系统基于微加工工艺和叠层封装技术，设计柔性电极、互连导线、处理电路多单元一体化结构，采用柔性印刷电路和蛇形互连设计实现整体器件的可延展性。信号采集器件重量仅12.5g，电极贴片厚度仅0.25mm，可与母体腹壁共形贴合，提升佩戴舒适度，同时采集信号通过蓝牙无线传输，便于随体长时间连续的胎心监护。临床应用结果表明，该系统可准确检测胎心率、母体心率和宫缩活动，经与商用飞利浦胎儿监护仪对比，结果具有良好的一致性。同时，该无线胎心电监测系统可实现长达6小时以上的连续胎心电监测，为胎儿的健康监护提供有力保障。