Luis Moreno Hagelsieb

Immobilization of DNA on CMOS compatible materials

The main interface and interconnection materials normally used in complementary metal-oxide semiconductor (CMOS) integrated circuit processing, i.e. silicon oxides and aluminum, were evaluated with regards to deoxyribonucleic acid (DNA) attachment. We investigated and quantified the influence of various techniques of fabrication of the silicon oxide on DNA binding obtained by four different biochemical processes. Regarding aluminum, we found that it only binds DNA in the presence of its natural oxide and that it is severely degraded by one of the three typical biochemical processes. Optimal process conditions for DNA binding on silicon oxides with aluminum compatibility are finally derived

DNA electrical detection based on inductor resonance frequency in standard CMOS technology

Several electrical methods have been studied for the detection of DNA hybridization on silicon chips, using capacitance or resistance changes of micro-arrays of electrode fingers. In this work, we studied the possibility of detecting DNA by the measurement of the resonance frequency shift of an inductor designed on Si substrate. Self-resonance frequency shift as large as 10 GHz before and after DNA hybridization has been measured for inductors made from standard CMOS process with a protective oxide coating and a DNA amplification based on silver enhancement.

Mechanical properties of anodic aluminum oxide for microelectromechanical system applications

Aluminum oxide features good electrical properties such as high dielectric constant and high breakdown voltage. During these last years it has been introduced for the fabrication of metal oxide semiconductor and metal insulator metal capacitors. In the present paper, the mechanical properties of anodic Al2O3 are addressed as well as its interest for microelectromechanical system applications including membranes or cantilevers for humidity, flow, pressure, or biological sensors

Fluid characterization by interdigitated electrodes sensors

The purpose of this paper is to present the concept of a complete fluid characterization microsystem. This system is composed of three parts. The first is a classical two-dimensional sensor using interdigitated (IDA) aluminum electrodes covered by anodized alumina. The second part is a CMOS digital circuit which is used to modulate the sensor topology. The work of the last part is to transduce the sensor useful signal in an oscillating voltage.

Wireless microsensors system for monitoring breathing activity

A portable, non-invasive and easy to operate wireless system has been developed for monitoring the breathing activity of patient. The system is composed of a capacitive microsensor (airflow-humidity sensor) integrated on a silicon chip and of a Negative Temperature Coefficient thermistor; both are coupled to a Radio Frequency wireless link. The sensitive part of the microsensor is an array of interdigitated metallic electrodes covered by 100 nm-thick dense anodized aluminum oxide layer. The breath water vapor is adsorbed over the interdigitated electrode and changes the sensor characteristic capacitance. This modulated signal is then digitized and either stored in a memory or directly transmitted to a monitor through the short distance RF link. Full size of the microsensor is less than 1 cm/sup 2/ and can be easily implemented in a classical adhesive bandage. This microsystem is proposed for monitoring sleep-disordered breathing as well as breathing rhythm of athletes during effort.

Bio-compatible Insulated Substrate Impedance Transducers

An alternative smart sensing paradigm to largescale biocompatible integration has been explored. Traditionally, conductive bio-labels detection profits from planar interdigitated electrodes (IDE) encapsulated between for instance a top thin alumina layer and a bottom thick silicon dioxide. Despite demonstrating good electrostatic sensitivity at strong micro-labels densities, such patterns however require sub-micron shrinking to work below 30% conductive labels coverage. We therefore derived a spectroscopic field-effect transducer from micrometric DDE coupled to a thinly insulated surface-doped silicon channel. Thanks to capacitance enhancement that results between electrodes and semiconductor, label-induced field-effect modulation of channels conductance gives rise to an intrinsic dielectric relaxation constant change subsequently measured by impedance spectroscopy. So-called Insulated Substrate Impedance Transducers (ISIT) have thereby been designed to sense an inter-digital impedance spectrum change following a frequency-dependent multi-parameter approach. In demonstration, metallic grains densities ranging from 1.2% to 17%, ensued from 0 to 1 nM concentrations of silver-labeled 30 bp DNA targets were sensed in air on 100 * 100 mu m/sup 2/ arrays through conductance and capacitance variations by factors of 6 and 3, respectively. Our presentation will focus on simulation, optimization and characterization of ISITs electrical operation, and present on-chip tuning possibilities associated with substrate back-contact biasing.