On-Chip Liquid and Gas Flow Rate Sensing via Membrane Deformation and Bistability Probed by Microwave Resonators

Abstract

Precise monitoring of fluid flow rates constitutes an integral problem in various lab-on-a-chip applications. While off-chip flow sensors are commonly used, new sensing mechanisms are being investigated to address the needs of increasingly complex lab-on-a-chip platforms which require local and non-intrusive flow rate sensing. In this regard, the deformability of microfluidic components has recently attracted attention as an on-chip sensing mechanism. To develop an on-chip flow rate sensor, here we utilized the mechanical deformations of a 220 nm thick Silicon Nitride membrane integrated with the microfluidic channel. Fluid flow induces deformations on the membrane, which is electronically probed by the changes in the capacitance and resonance frequency of an overlapping microwave resonator. By tracking the resonance frequency, both liquid and gas flows were probed with the same device architecture. For liquid flow experiments, a secondary sensing mechanism emerged when it was observed that steady liquid flow induces periodic deformations on the membrane. Here, the period of membrane deformation depends on the flow rate and can again be measured electronically by the microwave sensor. Flow rate measurements based on the deformation and instability of thin membranes demonstrate the transduction potential of microwave resonators for fluid-structure interactions at micro and nanoscales.

A Miniaturized MEMS Accelerometer with Anti-Spring Mechanism for Enhancing Sensitivity

“…Bistable mechanisms, composed of elastic beams or membranes, are widely employed across various MEMS applications, including microrobotics 36 , switch 37 , resonators 38 , sensors 39,40 , and actuator 41 , owing to their simplicity, low actuation energy, large stroke with small restoring forces, and snap-through behavior. Among these, beam-type bistable mechanisms are particularly prevalent in MEMS as compliant mechanisms, favored for their straightforward structure and negative stiffness properties.…”

Dielectric Detection of Single Nanoparticles Using a Microwave Resonator Integrated with a Nanopore

“…After the process on the top surface was completed, we proceeded with membrane fabrication. 26 A window was opened at the bottom of the wafer with anisotropic etching of Si 3 N 4 to enable backside KOH wet etching. Si and SiO 2 were etched by KOH until the top Si 3 N 4 layer was suspended, which forms the thin membrane.…”

“…Beyond single nanoparticle sensing reported here, microwave capacitive sensing can be applied to dynamically characterize ion distributions inside nanoscale channels to provide a novel characterization technique for nanofluidics. 40−42 Orthogonal measurement modalities can also be seamlessly integrated with microwave sensors, such as by incorporating UV-absorbing nanomaterials for liquid characterization, 43 integrating flexible membranes for fluid flow measurements, 26,44 and coupling to mechanical resonators for deflection-based mass determination. 45…”

Yerel olmayan elastisite teorisine göre üç mesnetli nano kirişin doğrusal olmayan titreşim davranışı

“…Nano elektromekanik sistemlerin popülaritesi, küçük boyutlarından dolayı son birkaç on yılda oldukça artmıştır. Virüs, kanser gibi hastalıkların teşhisinde kullanılan biyosensörler, gaz dedektörleri, basınç sensörleri, jiroskobik sensörler gibi yapılarda NEMSler günümüzde sıklıkla kullanılmaktadır [1][2][3]. Benzersiz özellikleri nedeniyle bilim insanları nano kiriş [4,5], nano plaka [6,7], nano kabuk [8,9] gibi nano elemanlar üzerinde oldukça yoğun teorik çalışmalar yapmaktadır.…”