Anthony Treizebre

Planar excitation of Goubau Transmission Lines for THz BioMEMS

We propose and demonstrate an original planar excitation of a single wire transmission line also known as Goubau-Line (G-Line). The excitation is based on an electromagnetic transition between a coplanar waveguide and the desired G-line in a planar configuration. We present some characteristics for this line such as its electromagnetic spatial distribution, its velocity, and results in the frequency domain analysis for the transitions. We will also show some results concerning the shape of the G-line and its influence on the transmission level. From these results, we show that there is a great interest for these structures in the field of biological characterization.

Cold plasma functionalized TeraHertz BioMEMS for enzyme reaction analysis.

In this paper, we describe the development, functionalization and functionality testing of a TeraHertz (THz) Bio-MicroElectroMechanical System (BioMEMS) dedicated to enzyme reaction analysis. The microdevice was fabricated by mixing clean room microfabrication with cold plasma deposition. The first is used to build the microfluidic circuits and the THz sensor, while the later serves for the polymerization of allylamine using a homemade glow discharge plasma reactor for a subsequent immobilization of enzymatic biocatalysts. Thermal stability of the deposited plasma polymer has been investigated by infrared spectroscopy. Fluorescent detection confirmed the efficiency of the immobilization and the enzyme hydrolysis into the BioMEMS microchannels. For the first time, the progression of the hydrolysis reaction over time was monitored by the THz sensor connected to a vectorial network analyzer. Preliminary results showed that sub-THz transmission measurements are able to discriminate different solid films, various aqueous media and exhibit specific transmission behavior for the enzyme hydrolysis reaction in the spectral range 0.06-0.11 THz.

Co-integrated microfluidic and THz functions for biochip devices

TeraHertz (THz) spectroscopy is becoming an alternative way to probe biological interactions in real-time conditions. However, accurate and reproducible THz measurements of aqueous solutions, largely represented in life sciences, remain difficult. A THz microsystem which couples both electromagnetic and microfluidic integrated functions is presented here. Its technological process is accurately detailed and enables easy designs of advanced THz and microfluidic functions. It is composed of the deposition of gold wires on a glass wafer to guide the THz waves. Then, a whole silicon wafer is bonded by using a thermosensitive-polymer thermo-compression. Silicon is deep-etched to create the microchannels which are finally covered with a second glass wafer. This bonding–etching process enables huge freedom and independence for electromagnetic and microfluidic designs. The technological process characterization has shown that the manufactured biochip is compatible with pressures up to 37 bar. First measurements with empty and water-filled channels have been carried out and have shown the ability to perform THz spectroscopy inside the chip. Then, first measurements on proteins have been performed and shown the system ability to probe protein concentration. This kind of microfluidic microsystem, allowing complex design for integrated electronic and microfluidic circuits, defines a true new instrumental way for life science investigations.

Subterahertz characterization of ethanol hydration layers by microfluidic system

Characterizations of ethanol hydration layers are examined through subterahertz spectroscopy of water/ethanol mixtures by using a microfluidic system. A three-component model is used to explain measurements discrepancies with the Lambert–Beer law and to determine ethanol hydration shell absorption. Moreover, the hydration shell distribution is compared with molecular dynamics simulations with a good agreement. Ethanol hydration number is then computed and it can quickly characterize only the first water hydration layer or the whole hydration shell, depending on the chosen extraction model.

Corrugated Goubau Lines to Slow Down and Confine THz Waves

Corrugations on planar Goubau lines are presented in order to slow down and focus electromagnetic waves. A propagation effective index shift is observed between corrugated and non-corrugated planar Goubau lines. Influence of the corrugation geometrical parameters is studied. Two original methods based on Bianco-Parodi differential measurements or on THz interferometer structure are validated. Finally, the effect of corrugating lines on unwanted substrate modes reject is discussed with experimental and parametric simulation studies. The wave stronger “attachment” in corrugated configurations is demonstrated.

THz POWER DIVIDER CIRCUITS ON PLANAR GOUBAU LINES (PGLs)

Terahertz spectroscopy is a new tool for real time biological analysis. Unfortunately, investigations on aqueous solutions remain di-cult and need to work on nanovolumes. Integrated Terahertz instrumentation remains a challenge. We demonstrate that Planar Goubau Line (PGL) technology could bring a real practical solution to reach this goal. This study provides the design, fabrication and test results of passive PGL components like loads and power divider. These PGL components are designed, simulated, fabricated and measured with a Vectorial network analyser (VNA). Simulation and test data support PGL component designs. PGL components operate over a wide frequency range from 0.06 to 0.325THz.

TERAHERTZ SPIRAL PLANAR GOUBAU LINE REJECTORS FOR BIOLOGICAL CHARACTERIZATION

Terahertz spectroscopy brings precious complementary information in life science by probing directly low energy bindings inside matter. This property has been demonstrated on dehydrated substances, and interesting results are obtained on liquid solutions. The next step is the characterization of living cells. We have successfully integrated THz passive circuits inside Biological MicroElectroMechanical Systems (BioMEMS). They are based on metallic wires called Planar Goubau Line (PGL). We demonstrate that high THz measurement sensitivity can be reached with new design based on spirals. But we show that the principal interest of this design is its high spatial resolution below the wavelength size compatible with living cell investigation.

Highly sensitive terahertz spectroscopy in microsystem

We herein present a microfluidic system dedicated to THz spectroscopy of aqueous solutions. This device is able to reach a state of the art sensitivity of 5 mg mL−1, while requiring only small sample quantities and a low power source. Hydration of BSA, lysozyme and chymotrypsine proteins is studied inside microchannels and hydration numbers are computed, showing that the developed system is well suited for quantitative analysis. Moreover, coupled with advanced chemometrics algorithms, this system can become a tool for fundamental research and for the understanding of biochemical processes. Here, the hydration shell structure is discussed by chemometric analysis of the measured absorption spectra. Two spectral behaviours are observed and can be explained by Molecular Dynamics simulations. This methodology could be considered as a key element of a lab-on-a-chip for biological liquid metrology.

Nanoscale devices for online dielectric spectroscopy of biological cells

Nanoscale probes have been developed for the online characterization of the electrical properties of biological cells by dielectric spectroscopy. Two types of sensors have been designed and fabricated. The first one is devoted to low (<10 MHz) frequency range analysis and consists of gold nanoelectrodes. The second one works for high (>40 Hz) frequency range analysis and consists of a gold nanowire. The patterning of the sensors is performed by electron beam lithography. These devices are integrated in a microfluidic channel network for the manipulation of the cells and for the improvement of the performances of the sensors. These devices are used for the analysis of a well-characterized biological model in the area of the ligand-receptor interaction. The purpose is to monitor the interaction between the lactoferrin (the ligand) and the nucleolin and sulfated proteoglycans (the receptors) present or not on a set of mutant Chinese hamster ovary cell lines and their following internalization into the cytoplasm. Initial measurements have been performed with this microsystem and they demonstrate its capability for label-free, real-time, analysis of a dynamic mechanism involving biological cells.

In-flow detection of ultra-small magnetic particles by an integrated giant magnetic impedance sensor

We have designed and fabricated a microfluidic system made of glass and polydimethylsiloxane. A micro-magnetometer has been integrated to the system. This sensor is made of a giant magneto-impedance wire known to have very high magnetic sensitivity at room temperature. A liquid-liquid segmented multiphase flow was generated in the channel using a Y-shaped inlet junction. The dispersed phase plugs contained superparamagnetic iron oxide (20 nm) nanoparticles at a molar concentration of 230 mmol/l. We have shown both theoretically and experimentally that in-flow detection of these nanoparticles is performed by the microsystem for concentration as small as 5.47 × 10−9 mol. These performances show that it is conceivable to use this system for ex-vivo analysis of blood samples where superparamagnetic iron oxide nanoparticles, initially used as magnetic contrast agents, could be functionalized for biomarkers fishing. It opens new perspectives in the context of personalized medicine.