Low-cost wireless temperature measurement has significant value in the food industry, logistics, agriculture, portable medical equipment, intelligent wireless health monitoring, and many areas in everyday life. A wireless passive temperature sensor based on PCB (Printed Circuit Board) materials is reported in this paper. The advantages of the sensor include simple mechanical structure, convenient processing, low-cost, and easiness in integration. The temperature-sensitive structure of the sensor is a dielectric-loaded resonant cavity, consisting of the PCB substrate. The sensitive structure also integrates a patch antenna for the transmission of temperature signals. The temperature sensing mechanism of the sensor is the dielectric constant of the PCB substrate changes with temperature, which causes the resonant frequency variation of the resonator. Then the temperature can be measured by detecting the changes in the sensor’s working frequency. The PCB-based wireless passive temperature sensor prototype is prepared through theoretical design, parameter analysis, software simulation, and experimental testing. The high- and low-temperature sensing performance of the sensor is tested, respectively. The resonant frequency decreases from 2.434 GHz to 2.379 GHz as the temperature increases from −40 °C to 125 °C. The fitting curve proves that the experimental data have good linearity. Three repetitive tests proved that the sensor possess well repeatability. The average sensitivity is 347.45 KHz/°C℃ from repetitive measurements conducted three times. This study demonstrates the feasibility of the PCB-based wireless passive sensor, which provides a low-cost temperature sensing solution for everyday life, modern agriculture, thriving intelligent health devices, and so on, and also enriches PCB product lines and applications.

An aluminum nitride (AlN) based patch antenna-type high-temperature wireless passive sensor is reported to operate as both a sensor and an antenna, which integrates in situ measurement/sensing with remote wireless communication at the same time. The sensor is small, easy to manufacture, highly sensitive and has a high operating temperature; it can be used in high-temperature, chemically corrosive and other harsh environments. The sensing mechanism of the sensor, the dielectric constant of the AlN ceramic substrate, increases with rising temperature, which reduces the resonant frequency of the sensor. Thus, the temperature can be measured by detecting changes in the sensor’s resonant frequency. High-Frequency Simulation Structure (HFSS) software is used to determine the structure and size of the sensor, which is then fabricated using thick-film technology. The substrate of the sensor is AlN ceramic due to its outstanding thermal resistance at high temperature; and its conductors (the radiation patch and the ground under the substrate) are silver-palladium alloy sintered form silver–palladium paste. A vector network analyzer reveals that the sensor’s operating range extends to 700 °C. Furthermore, its resonant frequency decreases from 2.20 GHz to 2.13 GHz with increasing temperature from room temperature (25 °C) to 700 °C, with an absolute sensitivity of 104.77 KHz/°C. Our work verifies the feasibility of measuring high temperatures using AlN-based patch antenna wireless passive temperature sensors, and provides a new material and temperature sensitive structure for high-temperature measurement in harsh environments.

Bone drilling is a common surgical operation, which often causes an increase in bone temperature. A temperature above 47 °C for 60 s is the critical temperature that can be allowed in bone drilling because of thermal bone osteonecrosis. Therefore, thermal management in bone drilling by a rotating heat pipe was proposed in this study. A new rotating heat pipe drill was designed, and its heat transfer mechanism and thermal management performance was investigated at occasions with different input heat flux and rotational speed. Results show that boiling and convection heat transfer occurred in the evaporator and film condensation appears in the condenser. The thermal resistance decreases with the increase of the rotational speed at the range from 1200 to 2000 rpm and it decreases as the input heat flux rises from 5000 to 10,000 W/m2 and increases at 20,000 W/m2. The temperature on the drill tip was found to be 46.9 °C with an input heat flux of 8000 W/m2 and a rotational speed of 2000 rpm. The new designed rotating heat pipe drill showed a good prospect for application to bone drilling operations.

On the basis of the study of green surfactant alkyl polyglucoside that was synthesized from starch or glucose and fatty alcohol by direct method, the reaction mechanism was discussed and the macroscopic reaction kinetics model was proposed and established. The kinetics model between the concentration of glucose(CA) and reaction time (t) was as follows: ln(CA—0.00025) = —(Kt+2.08). The method of establishing kinetics model can be popularized to the kinetic study of other alkyl polyglucoside.

No abstract