A metamaterial-inspired temperature stable inkjet-printed microfluidic-tunable bandstop filter

Abstract

A low-cost and disposable microfluidic-tunable bandstop filter is presented which is fabricated utilizing a novel inkjetprinting based microfluidics platform. The proposed bandstop filter is based on a split-ring-resonator (SRR) unit cell embedded within the ground of a co-planar waveguide (CPW) transmission line. By loading the capacitive gap of the SRR with an array of fluids with different permittivities, the resonant frequency of the resonator can be tuned over a wide bandwidth. Utilizing only 6 μL of fluid, which is approximately one twentieth of a drop of water, a 30 %, or 0.4 %/ε r change in resonant frequency can be achieved which is higher than current cleanroom-fabricated microfluidic RF devices in the literature. The high temperature stability of the low-cost microfluidic filter is presented, which demonstrates below 1 % variance in resonant frequency for operating temperatures ranging from 273 K to 332 K.

Additively Manufactured Microfluidics-Based “Peel-and-Replace” RF Sensors for Wearable Applications

“…10 from 3.9 to 2.19 GHz when an empty channel is replaced with a water-filled channel. To the best of authors' knowledge, this sensor prototype features the highest sensitivity compared with other recently published microwave/RF microfluidic sensors, including inkjet-printed sensors (e.g., 28% from empty to water reported in [14]), as well as sensors fabricated by traditional soft lithography methods (e.g., 21% from empty to water reported in [9]). …”

“…The strength of the resonance decreases for larger frequency shifts, and there is a limit of the frequency shift above which the resonance becomes too weak to be measured [14]- [16]. So, on one hand, if a sensor has a superior sensitivity, then the shifted resonant frequency of a high-permittivity fluid may already be in the zone that has greater than −10-dB peak attenuation.…”

Additively Manufactured Nanotechnology and Origami-Enabled Flexible Microwave Electronics

“…Fully inkjet-printed flexible microfluidic channels are under development and are expected to be reported in the near future. In the flexible prototype reported in [39], a Dimatix DMP-2800 series printer is used to inkjet print a silver nanoparticle ink onto the paper substrate. After curing the silver ink, a layer of polymer (SU-8) is printed over the metalized pattern to be used as an adhesive to seal the channel as well as the isolation layer between the filling fluids and the metalized pattern.…”

Inkjet‐Printed Smart Skins and Wirelessly‐Powered Sensors for Wearable Applications

“…Right: Insertion loss of the microfluidic-tunable bandstop filter with different fluids in the channel in simulation and measurement. Source: Su et al 2014[35]. Reproduced with permission of IEEE.…”