On the Wireless Microwave Sensing of Bacterial Membrane Potential in Microfluidic-Actuated Platforms

Abstract

The investigation of the electromagnetic properties of biological particles in microfluidic platforms may enable microwave wireless monitoring and interaction with the functional activity of microorganisms. Of high relevance are the action and membrane potentials as they are some of the most important parameters of living cells. In particular, the complex mechanisms of a cell’s action potential are comparable to the dynamics of bacterial membranes, and consequently focusing on the latter provides a simplified framework for advancing the current techniques and knowledge of general bacterial dynamics. In this work, we provide a theoretical analysis and experimental results on the microwave detection of microorganisms within a microfluidic-based platform for sensing the membrane potential of bacteria. The results further advance the state of microwave bacteria sensing and microfluidic control and their implications for measuring and interacting with cells and their membrane potentials, which is of great importance for developing new biotechnologically engineered systems and solutions.

Superheterodyne Microwave System for the Detection of Bioparticles With Coplanar Electrodes on a Microfluidic Platform

“…In a set of initial experiments, air bubbles were introduced into the tubes to provide a higher permittivity contrast to calibrate the system. The preparation of the liquid medium followed the method described in a previous work [10], which is composed of 0.2 µm-filtered water with 500 ppm of polyethylene oxide (PEO) cured for more than 4 weeks; the PEO was taken from a 10 4 ppm of 0.4 MDa prepared stock.…”

“…Next, the mixture is introduced into the fluid tubes from this reservoir at a flow rate of 10 µL/ min by the pressure pump, which is connected to a flow controller with a resolution of 1 µL/ min. Then, the mixture flows through the microchannel in which a balance of hydrodynamic forces constraints the microparticles to focus at its centerline [10], and passing through the electromagnetic fields generated by the electrodes. Finally, the mixture is collected in a second reservoir (waste) at the outlet of the microchannel to be later recycled.…”

“…Finally, at the micrometric scale, focusing and sorting of bioparticles is a challenge that can be overcome through the advantages offered by microfluidic technologies, which typically make use of microchannels with cross-sections in the order of 100 µm or smaller. These characteristics enable automated control and position of bioparticles without mechanical moving parts, and presenting little noise generation in the process [10].…”

Experimental Verification of Dielectric Models with a Capacitive Wheatstone Bridge Biosensor for Living Cells: E. coli

“…In recent years, the exploitation of their intrinsic electrical properties has emerged as an appealing approach for concentrating and detecting bacteria [ 1 ]. Various electrical sensing technologies have been developed, including micro-fabrication technology, nano-fabrication technology [ 4 ], and microwave microorganism detection technology, based on microfluidic platforms that are used to sense the membrane potential of bacteria [ 5 , 6 ]. Furthermore, bacteria trapping and detection can be implemented with lab-on-chip devices [ 7 ].…”

A Water/Ion Separation Device: Theoretical and Numerical Investigation

“…Recently, synthetic nano-conduits have been introduced, such as artificial water channels (AWCs), to develop highly selective membranes for water desalination [16]. In a neighboring research field with biological interest, bacterial membrane potential dynamics have been investigated for exploitation in microfluidicbased platforms [17].…”