Low-temperature co-fired ceramic (LTCC) technology for development of sensors for emerging applications

LTCC technology continues to be an attractive option for fabrication of sensors, sensor packages and complex micro-systems. The objective of this work is to present LTCC sensors developed by CSEM Brasil with a focus on capacitive type wireless soil moisture sensor (SMS) for precision farming that is capable to measure soil moisture in real time and transmit the data to 80 m distance (line of sight). The sensor is constructed from 4 functional blocks: PCB base including the capacitive electrodes, LTCC block carrying the electronics and soldered on PCB, voltage regulator and wireless unit. Tests conducted with 28 prototypes reveal that the sensor response is over 1.00 V at full humidity and reproducible whilst the battery consumption is around 200 mW, permitting a battery life of 5 years at a measurement frequency of 1 sampling per minute.