Monolithic Microwave-Microfluidic Sensors Made with Low Temperature Co-Fired Ceramic (LTCC) Technology

Abstract

This paper compares two types of microfluidic sensors that are designed for operation in ISM (Industrial, Scientific, Medical) bands at microwave frequencies of 2.45 GHz and 5.8 GHz. In the case of the first sensor, the principle of operation is based on the resonance phenomenon in a microwave circuit filled with a test sample. The second sensor is based on the interferometric principle and makes use of the superposition of two coherent microwave signals, where only one goes through a test sample. Both sensors are monolithic structures fabricated using low temperature co-fired ceramics (LTCCs). The LTCC-based microwave-microfluidic sensor properties are examined and compared by measuring their responses for various concentrations of two types of test fluids: one is a mixture of water/ethanol, and the other is dopamine dissolved in a buffer solution. The experiments show a linear response for the LTCC-based microwave-microfluidic sensors as a function of the concentration of the components in both test fluids.

Fabrication and Applications of Microfluidic Devices: A Review

“…Low-temperature cofired ceramic (an aluminum oxide-based material) can be employed to fabricate microfluidic platforms [ 17 , 32 ]. The properties that recommend ceramics for microchips are their unique surface chemistry, good resistance to corrosive environments, and good stability at high temperatures [ 17 , 25 ].…”

An LC Wireless Microfluidic Sensor Based on Low Temperature Co-Fired Ceramic (LTCC) Technology

“…Compared with the reported LTCC microfluidic biosensor based on electrochemical methods, absorption photometry, microwave resonators, and capacitive sensing with interdigitated capacitors (IDCs) [ 39 , 40 , 41 , 42 , 43 ], we provided a wireless detection method without using fluorescent labeling, complex chemical reactions, and wire connections. Moreover, the designed sensor was more sensitive to changes in the permittivity of liquids within a wide range of permittivity than most of the reported microwave electromagnetic sensors.…”

Microfluidic Modules Integrated with Microwave Components—Overview of Applications from the Perspective of Different Manufacturing Technologies

“…Another example is the microstrip resonator, made on DuPont 951 PX LTCC [ 101 ]. The resonator was designed with the microchannel placed in the cavities of the split-ring resonator.…”

“…After the measurements, it was observed that changes in the volume of ethanol in deionized water, as well as changes in dopamine content, affected the response of the sensor. In [ 101 ], another device was presented. Such a module was also made using the LTCC material as a substrate, but the microwave circuit consisted of the Wilkinson divider, the symmetric transmission lines, and the rat-race hybrid, similar to the solution shown in [ 49 ].…”

“… The photo of the manufactured detector ( a ) and the X-ray image with the microwave circuit of the detector ( b ) [ 101 ]. …”