Microwave resonator array with liquid metal selection for narrow band material sensing

Abstract

A microwave resonator array is integrated with liquid metal to select an individual resonator response within a resonator array, enabling simple and accurate analysis for dielectric sensing. Galinstan, a liquid metal, acts as a multiplexer by inducing a capacitive load to the nearby resonator, lowering its resonant frequency, and thereby isolating its resonant response from other resonators in the array. The liquid metal could be positioned within a fluidic channel to be above any of the resonators, which tuned the resonant frequency from 3.9 to 3.3 GHz where it can be analyzed individually. The resonators showed a consistent response to liquid metal tuning, with tuning error measured below 30 MHz (5%). The sensor also exhibited stable sensitivity to test materials placed on the selected resonator, with a maximum resonant frequency shift of 300 MHz for a dielectric test material (ε = 10.2) and almost no variation in resonant amplitude. The selected resonant response was only sensitive to materials on the selected resonator, and was unaffected by test materials, even when placed on other resonators. The presented design enabled robust and accurate detection of materials using planar microwave resonators that can be controlled at a user’s convenience, specifically for use in systems where multiple parameters or system settings may need to be individually determined.

Integrated Microwave Antenna/Sensor for Sensing and Communication Applications

“…It is also possible to tune these two-port sensors utilizing a 3-D printed channel on microwave split-ring resonators (SRRs) [15]. This tuning property of a two-port microwave device can be used for sensing different dielectric materials using multiple resonators [16]. For example, in space vehicles, it is crucial to control the attitude of several machines (including the reaction wheels) and measure the torque using an angular displacement sensor.…”

“…The quality factor is also a function of resonance frequency and −3 dB bandwidth (S 21 ). In [16], only the real part of permittivity is expressed as a function of f 0 . In [47] and [49], ethanol/water mixtures and acetone/water mixtures are sensed, respectively, but their dielectric properties are not characterized.…”

3D-printing fabrication of microwave-microfluidic device for droplets network formation and characterisation

“…Liquid metal can be injected into void channels to form irregular shaped, spiral electrodes within 3D-printed microchip electrophoresis devices 20 . 3D printing technologies have also been applied to microwave instrumentation, such as waveguides, resonators, and antennas [21][22][23] , incorporating liquid metals as a tool to impose microwave properties on the devices 24 . Additionally, planar microwave resonators have been attached to 3D-printed microfluidic devices for the analysis of flowing liquid materials 25 .…”

Programmable Multiwavelength Radio Frequency Spectrometry of Chemophysical Environments through an Adaptable Network of Flexible and Environmentally Responsive, Passive Wireless Elements

“…Modern processing techniques enable a more focused cousin of this approach, wherein matter is organized into structures that interact with radiation in a directed way, such as to exhibit resonance phenomena. [14][15][16][17] This approach can be used to create more selective/sensitive sensors that are typically intended to measure a single value. [18][19][20][21] A common example of this is RF sensors, wherein conductive traces are patterned so as to resonate when excited by RF waves.…”