A miniaturized silicon based device for nucleic acids electrochemical detection

In this paper we describe a novel portable system for nucleic acids electrochemical detection. The core of the system is a miniaturized silicon chip composed by planar microelectrodes. The chip is embedded on PCB board for the electrical driving and reading. The counter, reference and work microelectrodes are manufactured using the VLSI technology, the material is gold for reference and counter electrodes and platinum for working electrode. The device contains also a resistor to control and measuring the temperature for PCR thermal cycling. The reaction chamber has a total volume of 20 μL. It is made in hybrid silicon–plastic technology. Each device contains four independent electrochemical cells.Results show HBV Hepatitis-B virus detection using an unspecific DNA intercalating redox probe based on metal–organic compounds. The recognition event is sensitively detected by square wave voltammetry monitoring the redox signals of the intercalator that strongly binds to the double-stranded DNA. Two approaches were here evaluated: (a) intercalation of electrochemical unspecific probe on ds-DNA on homogeneous solution (homogeneous phase); (b) grafting of DNA probes on electrode surface (solid phase).The system and the method here reported offer better advantages in term of analytical performances compared to the standard commercial optical-based real-time PCR systems, with the additional incomes of being potentially cheaper and easier to integrate in a miniaturized device. Keywords: Electrochemical detection, Real time PCR, Unspecific DNA intercalato

Gate-Bias Induced RON Instability in p-GaN Power HEMTs

In this letter, we investigate the on-resistance ( RON ) instability in p-GaN power HEMTs induced by a positive or negative gate bias ( VGB ), following the application of a quasi-static initialization voltage ( VGP ) of opposite sign. The transient behavior of this instability was characterized at different temperatures in the 90–135 °C range. By monitoring the resulting drain current transients, the activation energy as well as time constants of the processes are characterized. Not trivially, both RON increase/decrease were found to be thermally activated and with same activation energy. We attribute the thermal activation of both RON increase/decrease to the charging/discharging of hole traps present in the AlGaN barrier in the region below the gate

Development of Si-based electrical biosensors: Simulations and first experimental results

In this work, we simulated and experimentally assessed the possibility to detect, through electrical transduction, hybridization of DNA molecules on MOS-like devices, having different dielectrics: SiO2, Si3N4 and SiO2/Si3N4/SiO2 (ONO). The electrical characterization was performed after the various functionalization steps, consisting of dielectric activation, silanization, DNA spotting and anchoring, and after the hybridization process, to test the devices effectiveness as DNA recognition biosensors. The experimental results were used to validate device simulations. The comparison shows the ability to determine a priori the DNA probe density needed to maximize the response. The results confirm that the structures analyzed are sensitive to the immobilization of DNA and its hybridization

Image data analysis in qPCR: A method for smart analysis of DNA amplification

In this paper, a method for the direct quantitative analysis of amplified DNA via q-Polymerase Chain Reaction (qPCR) in miniaturised silicon-based chip system is presented. The designed tool presented here allows the automatic extraction of meaningful information from input fluorescent images by means of digital image processing algorithm. In particular, a smart mathematical model, optimizing the integration of all the analysis steps of the fluorescence data from on chip multiple real time PCR, is described. Such a tool is able to load the digital input images, select and smartly detect the region of interest for fluorescence, elaborate the data input, calculate the average fluorescence values and finally, plot the fitted curve as output, giving also, for each well, both the Cycle Threshold (CT) and Slope parameters. Keywords: Image analysis, qPCR, LabonChip, Edge detection, Hough transfor

Reference Temperature Sensor for TMOS-Based Thermal Detectors

This paper presents a temperature sensor system providing the reference temperature of TMOS-based thermal detectors, in order to enable contactless absolute temperature measurements. The proposed system directly employs a few pixels of the TMOS detector as sensing element, thus detecting the local TMOS temperature, while the readout circuit is integrated on a separate chip. The readout circuit features a two-phase time-domain architecture, which provides biasing to the sensing element by alternatively switching between two different bias current values in subsequent phases. The temperature reading is converted to the digital domain thanks to a switched-capacitor 1-bit second-order sigma-delta ( $\Sigma \Delta$ ) analog-to-digital converter (ADC). The proposed readout system was fabricated in a 130-nm CMOS process and extensively characterized through measurements, together with the TMOS detector, realized in a 130-nm CMOS SOI technology and bonded on the same package. The proposed reference temperature sensor system, burning 10.8- $\mu \text{W}$ power, features 97-mK resolution when considering a 4096-ms conversion time and $0.13^{\circ} \text{C}$ peak-to-peak inaccuracy after three point calibration in the 15– $40^{\circ} \text{C}$ range, thus satisfying the characteristics for contactless human body temperature measurements

High Responsivity Thermopile Sensors Featuring a Mosaic Structure

This paper presents a detailed analysis of a micromachined thermopile detector featuring high responsivity and a versatile mosaic structure, based on 128 60 µm × 60 µm pixels connected in series and/or in parallel. The mosaic structure is based on the one employed for the thermal sensor known as TMOS, which consists of a CMOS-SOI transistor embedded in a suspended and thermally isolated absorbing membrane, released through microelectro mechanical system (MEMS) post-processing. Two versions of the thermopile detector, featuring different series/parallel connections, are presented and were experimentally characterized. The most performant of the two achieved 2.7 × 104 V/W responsivity. The thermopile sensors’ performances are compared to that of the TMOS sensor, adopting different configurations, and their application as proximity detectors was verified through measurements

An Integrated Thermopile-Based Sensor with a Chopper-Stabilized Interface Circuit for Presence Detection

This paper presents a sensor-readout circuit system suitable for presence detection. The sensor consists of a miniaturized polysilicon thermopile, realized employing MEMS micromachining by STMicroelectronics, featuring a responsivity value equal to 180 V/W, with 13 ms response time. The readout circuit is implemented in a standard 130-nm CMOS process. As the sensor output signal behaves substantially as a DC, the interface circuit employs the chopper technique in order to minimize offset and noise contributions at low frequency, achieving a measured input referred offset standard deviation equal to 1.36 μ V. Measurements show that the presented system allows successfully detecting the presence of a person in a room standing at 5.5 m from the sensor. Furthermore, the correct operation of the system with moving targets, considering people either walking or running, was also demonstrated

Dynamic RDS-on degradation analysis on power GaN HEMT by means of TCAD simulations and experimental measurement

International audienceThis paper deals with the dynamic RDS-on degradation of GaN HEMT for 650V application. An overview of different parameters impacting the performances of the devices were investigated experimentally. From temperature dependent characterisations the main trap at the origin of the degradation could be extracted. The signature of carbon in the GaN buffer could be confirmed by TCAD simulation, where the same trends were reproduced

Dynamic RDS-on degradation analysis on power GaN HEMT by means of TCAD simulations and experimental measurement

International audienceThis paper deals with the dynamic RDS-on degradation of GaN HEMT for 650V application. An overview of different parameters impacting the performances of the devices were investigated experimentally. From temperature dependent characterisations the main trap at the origin of the degradation could be extracted. The signature of carbon in the GaN buffer could be confirmed by TCAD simulation, where the same trends were reproduced