•The paper proposes a resonator-antenna integrated low profile wireless passive temperature sensor based on low temperature co-fired ceramic (LTCC).•To interrogate the sensor signal, a coplanar waveguide (CPW)-fed microstrip antenna, possessing a relatively large bandwidth, is fabricated on high-temperature resistant alumina ceramic.•The sensor has realized the temperature measurement within 400 °C at a 30-mm reading distance, with a measurement sensitivity of 0.24 MHz/°C.•The time domain gating method is introduced for filtering the background noise signal.•The sensor can be detected at extremely 13.5 cm using the open ended waveguide interrogation antenna.This paper proposes a resonator-antenna integrated microstrip antenna temperature sensor based on a low-temperature co-fired ceramic (LTCC), whose permittivity varies monotonously with the temperature. The dimensional design process was first analyzed in detail, and by combining the standard LTCC technology, the sensor was fabricated using 15 layers of a green tape. To interrogate the sensor, a coplanar waveguide (CPW)-fed microstrip antenna, possessing a relatively large bandwidth, was designed and optimized using high frequency structure simulator software, and then fabricated on alumina ceramic through a screen-printing process. The sensor was then tested on a developed high-temperature measurement system. Because the original detected sweep signal was difficult to distinguish, a time-domain (T-D) gating method for filtering a background signal was introduced. The extracted peak frequency was found to decrease linearly with an increase in temperature to within 400 °C at a 30-mm reading distance, with a measurement sensitivity of 0.24 MHz/°C. Simultaneously, the antenna polarity was found to have a significant influence on the readout signal. Finally, for the introduced T-D gating method, this study analyzes that the sensor can be sensed at a long distance when using a high-gain interrogation antenna. It is expected that the proposed sensor can be used in monitoring the temperature in a harsh environment.

•A new square capacitive cavity structure is designed.•The sacrifice paste is firstly introduced into the LTCC-based MEMS (micro electromechanical system) structure.•More favorable flatness of the sensor's sensitive membrane is realized.•Comparing with its predecessors, greater sensitivity of the sensor is presented.This paper presents a wireless capacitive pressure sensor based on LTCC (low temperature co-fired ceramic) technology, where the design, fabrication, and measurement of the sensor is demonstrated and discussed. Differ from traditional LTCC process flow, a unique process of screen-printing sacrifice layer has been introduced to avoid deformation of the capacitive embedded cavity during lamination or sintering, which leads to a better performance of the sensor. A greater sensitivity of the sensor, comparing with its predecessors, is showed during measurement. Finally ways for future optimization are proposed.

The current–voltage characteristics of GaAs/InxGa1−xAs/AlAs resonant tunneling diodes (RTDs) are a function of stress, and the current–voltage changes of RTDs with stress are attributed to the piezoresistive effect in RTDs. In order to study the piezoresistive effect in RTDs for application in micromachined mechanical sensors, the beam-mass structure based on RTDs is designed, fabricated and tested by the Wheatstone bridge test circuit. The test results show that the piezoresistive sensitivity of RTDs can be adjusted through the bias voltage, and the maximal piezoresistive sensitivity of RTDs with bias voltage at 0.618 V is 7.61×10−11 Pa−1, which is two orders higher than the minimal piezoresistive sensitivity (2.03×10−13 Pa−1) of RTDs with bias voltage at 0.656 V, and is also higher than the piezoresistive sensitivity of silicon material (5.52×10−11 Pa−1).