Micropumps and biomedical applications – A review

The microfluidics domain has been progressing rapidly recently, particularly considering its useful applications in the field of biomedicine. This paper presents a novel, microfluidics-based design for four fundamental circuit elements in electronics, namely resistor, inductor, capacitor, and memristor. These widely used passive components were fabricated using a precise and cost-effective xurography technique, which enables the construction of multi-layered structures on foil, with gold used as a conductive material. To complete their assembly, an appropriate fluid was injected into the microfluidic channel of each component: the resistor, inductor, capacitor, and memristor were charged with transformer oil, ferrofluid, NaCl solution, and TiO2 solution, respectively. The electrical performance of these components was determined using an Impedance Analyzer and Keithley 2410 High-Voltage Source Meter instrument and the observed characteristics are promising for a wide range of applications in the field of microfluidic electronics.

https://www.mdpi.com/2079-9292/8/9/960/pdf

Microfluidics-Based Four Fundamental Electronic Circuit Elements Resistor, Inductor, Capacitor and Memristor

This paper reports the theoretical study of two different passive RF inductors used to design a voltage-controlled oscillator (VCO) for wireless network at 5GHz The first inductor is designed using classic microelectronic technology with geometrical optimization and the second is made with etched silicon substrate The obtained results show a high quality factor Q max = 129 and Q max =159 respectively for the first and second inductors The self resonant frequencies are higher than 75 GHz and allow a large frequency excursion Moreover, we have used TSMC RF CMOS 013 sm technology and the ADS tool in order to design and analyze the responses of two different VCOs based on our RF spiral inductors The obtained results show a slightly difference between two VCOs Basically, the second inductor permits to ameliorate the power consumption and the tuning range of the VCO that reach: PC = 036 mW and TR = 166% Nevertheless, the phase noise is considerably the same: PN = −102 7dBc/Hz at 1 MHz of offset frequency

/pdf/analyzes-of-vco-performances-based-on-rf-spiral-inductors-3fhl5ovluo.pdf

Analyzes of VCO performances based on RF spiral inductors

This paper presents a T-junction microdroplet generator equipped with a pneumatic actuation for controlling the droplet size. The multi-layer device is compatible with rapid manufacturing using a desktop-based laser cutter to fabricate the fluidic and pneumatic layers. A T-junction fluidic layer sits at the bottom and the control layer consists of a pneumatic chamber, as well as inlet and outlet channels are placed at the top. Our results with pneumatic control showed that the generated droplet size is inversely proportional to the pressure inside the pneumatic chamber. Pneumatic pressure of up to 0.4 MPa showed a 38% reduction in droplet size compared to without control. The droplet size can additionally be regulated by controlling the relative flow rates of the continuous and dispersed fluid. Pneumatic actuation is advantageous, as it does not require additional fluid usage and the flow rate does not need to be ramped up to decrease the droplet size. The device presented in this paper with pneumatic control and fabrication ease provides an attractive method for microdroplet manipulation.

Development of a rapid manufacturable microdroplet generator with pneumatic control

This paper discusses the behavior of RF MEMS tunable microwave filter. We have modeled the distribution of magnetic field and electric current density in order to reveal the comportment of each device and to evaluate the relation between the frequency response and the microwave performances. From several modelling and simulations, we catch the resonance phenomenon for magnetic and electric fields at different conditions. Hence, in order to develop a reconfigurable MEMS ensuring a function of tunable band-pass filters, we have identified conditions allowing to vary the resonance frequency from Fres = 0.42 GHz to Fres = 1.85 GHz ensuring a large total variation of Tr = 340.5%. The structure is fabricated using SU-8 resin for circulating microchannels and sealing layers. The extracted parameters from measurements results and retro-simulation reveal a diminution of the total tuning range.

RF MEMS filter based on dual liquid variations

This letter presents the fabrication and the modeling of a continuously tuned microfluidic capacitor. On one hand its electrodes are realized by classical electrodeposition techniques and on the other hand, the lamination of SU-8 films allows superposing some microfluidic channels. According to the experimental results, the capacitor value increases continuously following the deionized (DI) water penetration in microchannels. The capacitance variations are comprised between Cmin = 0.52 pF and Cmax = 18.5 pF, allowing a wide tuning range that reaches 3460% at 500 MHz. The quality factor decreases from Qmax = 69 when the capacitor is empty to Qmin = 5.3 when it is fully filled with DI water. We have also investigated the theoretical aspects of our device by modeling the electric field and the current distributions inside the channels: when they are entirely filled with the DI water, the electric field is cancelled.

/pdf/fabrication-and-modeling-of-a-capacitor-microfluidically-3qm547xt8u.pdf

Fabrication and modeling of a capacitor microfluidically tuned by water

The effect of a dielectric liquid on the tunability of capacitor operating in RF domains is evaluated. The RF measurement shows a high variation of the resonant frequency accompanied with a low insertion loss. Moreover, the fluid positions between electrodes modify the capacitance value up to Tr = 6660% at 600 MHz. The quality factor decreases in response of water filling from Q max = 51.9 when it is empty to Q min = 1.49 when it is fully filled. According to the finite-element method analysis, the change of the dielectric permittivity influences the capacitor performances. Essentially, the tuning range of the capacitance and the quality factor could reach, respectively: Tr = 7660% and Q min = 35.

https://hal.laas.fr/hal-01415341/document

Tunable MEMS capacitor: influence of fluids

This paper presents the design and the fabrication of a continuously tunable RF MEMS capacitor using micro fluidics as a tuning parameter. The impedance variation principle is based on the modification of the capacitor gap permittivity produced by the presence of deionized water and its displacements in a channel inserted between electrodes. In addition, the electric field distribution changes in equiponderant way according to the DI water positions in the channel. This change modifies the capacitive coupling, the stored energy and consequently the self-resonant frequency. The fabrication process is based on two parts: metallic paths having a spiral form, and obtained by electroplating a 7 µm thick gold layer to constitute electrodes; and fluidic channels, realized by super imposing two SU-8 films. The measurements show a non-linear variation of the capacitor value according to the water positions. The tuning range is very large, reaching up to 4650% for the capacitance, and 335% for the resonant frequency. However, the quality factor reaches Qmax = 79 at 550 MHz if the capacitor is empty and decreases with the fluid displacements to Qmin = 3.13.

/pdf/design-and-fabrication-of-a-continuously-tuned-capacitor-by-ca6eiygu8t.pdf

Design and fabrication of a continuously tuned capacitor by microfluidic actuation

In this work, we have investigated the integration of an electroosmotic micropump allowing to generate droplets in two parallel flow focusing junctions. A novel design of the electroosmotic micropump with low voltage is proposed, acting as an active fluidic control to produce droplets of water-in-oil. Numerical studies are performed both on the micropump and the oil flow rate of the continuous phase. The simulations are conducted in terms of size and frequency of droplets issued from the device. Several ranges of applied voltage were applied to the micropump (2, 3.6, 5, and 10 V) for each oil flow rate value varying from 0.75 to 5.5 µl/min. Contrary to the pneumatic, piezoelectric or mechanical micropump, this integrated electroosmotic micropump is a versatile droplet generator allowing it to be used in microfluidic system.

Nizar Habbachi

Papers

Fabrication and modeling of a capacitor microfluidically tuned by water

Tunable MEMS capacitor: influence of fluids

Analyzes of VCO performances based on RF spiral inductors

Design and fabrication of a continuously tuned capacitor by microfluidic actuation

Design and modelling of droplet based microfluidic system enabled by electroosmotic micropump