Mohamed Amine Miled

Dielectrophoresis-Based Integrated Lab-on-Chip for Nano and Micro-Particles Manipulation and Capacitive Detection

We present in this paper a new Lab-on-Chip (LoC) architecture for dielectrophoresis-based cell manipulation, detection, and capacitive measurement. The proposed LoC is built around a CMOS full-custom chip and a microfluidic structure. The CMOS chip is used to deliver all parameters required to control the dielectrophoresis (DEP) features such as frequency, phase, and amplitude of signals spread on in-channel electrodes of the LoC. It is integrated to the LoC and experimental results are related to micro and nano particles manipulation and detection in a microfluidic platform. The proposed microsystem includes an on-chip 27-bit frequency divider, a digital phase controller with a 3.6° phase shift resolution and a 2.5 V dynamic range. The sensing module is composed of a 3 × 3 capacitive sensor array with 10 fF per mV sensitivity, and a dynamic range of 1.5 V. The obtained results show an efficient nano and micro-particles (PC05N, PA04N and PS03N) separation based on frequency segregation with low voltages less than 1.7 V and a fully integrated and reconfigurable system.

CMOS/microfluidic Lab-on-chip for cells-based diagnostic tools

We describe in this paper cells sensing and manipulation methods, as well as platforms based on Lab-on-chip devices. Among other contributions, new circuit and microfluidic techniques, and packaging methods are proposed for efficient cells manipulation and detection. The proposed devices include high-sensitivity sensing circuits (200 mV/fF), low-pressure liquid injection interfaces (<0.65 psi), low-voltage manipulation signals, direct-write microfluidic fabrication technique on top of CMOS based capacitive sensors. In addition, several types of electrode arrays (square and L-shaped) are used for the manipulation of various types of cells and particles.

Low-voltage dielectrophoretic platform for Lab-on-chip biosensing applications

We propose in this paper a platform for biopar-ticles mixing and detection in Lab-on-chip (LoC) based device dedicated to neurotransmitters analysis. The proposed biosensing device is characterized by a low voltage dielectrophoretic separation using novel L-shape electrodes. In addition to the mixing architecture enabling reaction between different particles, liquid was also sampled using the same electrodes. Our design works with different low voltages depending on particle size. It is tested with microspheres in the range of micrometers with an applied voltage less than 5V. The system dimensions ar e reduced to the minimum size such as it needs only few picolitre liquid samples. In addition to have a better control and separation, it is crucial to design many in-channel electrodes with minimum dimensions. Thus the microchannel includes 32 L-shape electrodes. The width of each electrode is 10 µm separated by 10 µm. Consequently, the width of the microchannel is 650 µm. The number of electrodes was choosen based on the number of outputs available on the monitoring electrical circuit.

A new CMOS/microfluidic interface for cells manipulation and separation in LoC devices

We propose in this paper a new fully integrated CMOS interface dedicated for cells manipulation and separation in LoC devices. The proposed interface includes all microelectronics circuits for dielectrophoretic manipulation and capacitive detection. It contains also an embedded frequency and phase micro controller to ensure several kinds of cells displacements such as rotation, translation and separation with a wide tunable frequency band of 250 kHz for LoC applications. Furthermore, the detection part is a charge-based capacitive measurement circuit with a high sensitivity of 10 mV for each 1 fF. This new chip is a fully integrated CMOS interface into a LoC device including both the microfluidic and the microelectronics structures. It represents one of the first microfluidic processors.

Hybrid Modeling Method for a DEP Based Particle Manipulation

In this paper, a new modeling approach for Dielectrophoresis (DEP) based particle manipulation is presented. The proposed method fulfills missing links in finite element modeling between the multiphysic simulation and the biological behavior. This technique is amongst the first steps to develop a more complex platform covering several types of manipulations such as magnetophoresis and optics. The modeling approach is based on a hybrid interface using both ANSYS and MATLAB to link the propagation of the electrical field in the micro-channel to the particle motion. ANSYS is used to simulate the electrical propagation while MATLAB interprets the results to calculate cell displacement and send the new information to ANSYS for another turn. The beta version of the proposed technique takes into account particle shape, weight and its electrical properties. First obtained results are coherent with experimental results.

Subthreshold transistor operation for a high sensitivity capacitive sensor

In this paper a low-power highly sensitive capacitor sensor is presented. When interfaced to interdigitated electrodes the corresponding circuit, based on capacitance variation, allows sensing microfluidic substances in lab-on-chip applications. We demonstrate the impact of the subthreshold region of transistor on the sensitivity of the capacitive sensor while it decreases the power consumption of the circuit. The proposed capacitive sensor circuit is implemented in 0.18 mum CMOS technology and the obtained sensitivity is 69 mV/fF.

Electrode robustness in artificial cerebrospinal fluid for dielectrophoresis-based LoC

In this paper, we present hybrid microelectronics / microfluidic Lab-on-Chip (LoC) platform intended for implantable medical microsystems for neurotransmitter detection. In vitro experiments were achieved using artificial cerebrospinal fluid (ACSF) from Tocris Bioscience where microspheres were immersed to test the behaviour of the designed LoC. One of main features of the proposed LoC platform is its thin thickness, including micro-channels and silicon CMOS chip. The latter is integrated into the glass top-layer of the LoC measuring 0.5 mm. The size of the device is 9 mm × 5 mm. the electrode architecture is composed of 8×2×2 L-shaped electrodes in a 650 μm channel width and 4 sites for interdigitited electrodes. 32 L-shaped electrodes were connected to a electronics circuit for cells manipulation using dielectrophoresis (DEP). The described LoC achieved an efficient separation within a concentration of 50 μl of a solution of microspheres, distilled water (DW) and 500 μl of ACSF. Beyond this concentration, electrode destruction was observed.

A Dynamic Decoder for First-Order

In this paper, we present a new decoder architecture for first-order sigma-delta analog-to-digital converters. This architecture is based on a dynamic decoding algorithm which is proposed to optimize the number of iterations required to decode sequences generated by the modulator, regardless of the conventional decoder. Optimization is achieved by an iterative algorithm that reduces the number of iterations using previously decoded values. The simulation results show a four-fold improvement over conventional decoding approaches and a gain of 1.69 dB for an 80-bit sequence and 4.01 dB for an 8-bit sequence regarding the decoding cycles. The proposed technique is implemented and tested on an field-programmable gate-array (FPGA) platform.

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In this paper, we describe a 0.18 mum CMOS capacitive sensor for microfluidic applications. This sensor features an interface circuit, which is incorporated with a calibration circuitry. We present the design and thereafter simulation and experimental results in the support of discussed issues throughout this paper. The proposed interface circuit offers the advantage of low complexity as well as sub femto Farad resolution.

Modulators Dedicated to Lab-on-Chip Applications

In this paper several electrodes architectures are modeled, implemented and compared in order to optimize the integration of hybrid micro-system for lab-on-a-chips (LoC). This study highlights the limitations of finite element simulations for a hybrid and complex micro-systems and propose new approach to overpass some fabrication constraints in a LoC design. The proposed LoC is based on dielectrophoresis for cell manipulation and capacitive sensing architecture. Particles used in this study has a diameter less than 10m which is close to the electrode dimensions. In this case conventional dielectrophoresis theory has some limitations. In order to handle particles in the range of micrometers, we describe four different electrode architectures which are the conventional square electrode array whose dimensions are 10m x 10m, the 10m width L-shaped electrode, the star-square electrode and the double side L-shaped electrodes. A comparison is presented at the end of the paper to highlight the advantages of each architecture