Carlotta Guiducci

CMOS DNA Sensor Array With Integrated A/D Conversion Based on Label-Free Capacitance Measurement

This paper presents a fully electronic label-free DNA chip in 0.5-mum CMOS technology, with 5-V supply voltage, suitable for low-cost highly integrated applications. The chip features an array of 128 sensor sites with gold electrodes and integrated measurement, conditioning, multiplexing and analog-to-digital conversion circuitry. The circuits measure capacitance variations due to DNA hybridization on the gold electrodes which are bio-modified by covalently attaching probes of known sequence. Specificity, repeatability and parallel detection capability of the fabricated chip are successfully demonstrated

DNA detection by integrable electronics

This paper presents a new electronic methodology to detect DNA hybridization for rapid identification of diseases, as well as food and environmental monitoring on a genetic base. The proposed solution exploits a new (electrical) capacitive measurement circuit, not requiring any prior labeling of the DNA (as it is often the case with the commonly employed optical detection). The sensitivity, the reliability, and the reproducibility of this device have been evaluated by experiments performed with a (non-integrated) prototype implementation, easily integrable in IC and/or micro-fabricated lab-on-a-chip.

Overview of Electrochemical DNA Biosensors: New Approaches to Detect the Expression of Life

DNA microarrays are an important tool with a variety of applications in gene expression studies, genotyping, pharmacogenomics, pathogen classification, drug discovery, sequencing and molecular diagnostics. They are having a strong impact in medical diagnostics for cancer, toxicology and infectious disease applications. A series of papers have been published describing DNA biochips as alternative to conventional microarray platforms to facilitate and ameliorate the signal readout. In this review, we will consider the different methods proposed for biochip construction, focusing on electrochemical detection of DNA. We also introduce a novel single-stranded DNA platform performing high-throughput SNP detection and gene expression profiling.

Wireless sensor networks: Enabling technology for ambient intelligence

Wireless sensor networks are one of the most rapidly evolving research and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field. and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field.

A Fully Electronic Label-Free DNA Sensor Chip

This paper presents a microfabricated DNA chip for fully electronic, label-free DNA recognition based on capacitance measurements. The chip has been fabricated in 0.5-mum CMOS technology and it features an array of individually addressable sensing sites consisting of pairs of gold electrodes and addressing logic. Read-out circuitry is built externally using standard components to provide increased experimental flexibility. The chip has been electrically characterized and tested with various solutions containing DNA samples. Significant capacitance variations due to DNA hybridization have been measured, thus showing that the approach represents a viable solution for a single chip DNA sensor array

Hydrogenated amorphous silicon ultraviolet sensor for deoxyribonucleic acid analysis

In this letter, we show the results achieved using a hydrogenated amorphous silicon photosensor for a “label-free” deoxyribonucleic acid (DNA) analysis based on the measurements of the absorbance in the ultraviolet range. The optimization of the sensor structure allowed us to bring the detection limit for a 30-mer DNA sample down to 1nM×cm, limited by the experimental setup. Taking advantage of the hypochromic effect, we also demonstrated the detection of single- and double-stranded DNA molecules in a melting experiment. From the noise characterization of our setup, we estimated the minimum DNA absorbance required to detect the occurrence of a hybridization/separation process to be below 10−3.

Label-Free Detection of Tobramycin in Serum by Transmission-Localized Surface Plasmon Resonance

In order to improve the efficacy and safety of treatments, drug dosage needs to be adjusted to the actual needs of each patient in a truly personalized medicine approach. Key for widespread dosage adjustment is the availability of point-of-care devices able to measure plasma drug concentration in a simple, automated, and cost-effective fashion. In the present work, we introduce and test a portable, palm-sized transmission-localized surface plasmon resonance (T-LSPR) setup, comprised of off-the-shelf components and coupled with DNA-based aptamers specific to the antibiotic tobramycin (467 Da). The core of the T-LSPR setup are aptamer-functionalized gold nanoislands (NIs) deposited on a glass slide covered with fluorine-doped tin oxide (FTO), which acts as a biosensor. The gold NIs exhibit localized plasmon resonance in the visible range matching the sensitivity of the complementary metal oxide semiconductor (CMOS) image sensor employed as a light detector. The combination of gold NIs on the FTO substrate, causing NIs size and pattern irregularity, might reduce the overall sensitivity but confers extremely high stability in high-ionic solutions, allowing it to withstand numerous regeneration cycles without sensing losses. With this rather simple T-LSPR setup, we show real-time label-free detection of tobramycin in buffer, measuring concentrations down to 0.5 μM. We determined an affinity constant of the aptamer-tobramycin pair consistent with the value obtained using a commercial propagating-wave based SPR. Moreover, our label-free system can detect tobramycin in filtered undiluted blood serum, measuring concentrations down to 10 μM with a theoretical detection limit of 3.4 μM. While the association signal of tobramycin onto the aptamer is masked by the serum injection, the quantification of the captured tobramycin is possible during the dissociation phase and leads to a linear calibration curve for the concentrations over the tested range (10-80 μM). The plasmon shift following surface binding is calculated in terms of both plasmon peak location and hue, with the latter allowing faster data elaboration and real-time display of the results. The presented T-LSPR system shows for the first time label-free direct detection and quantification of a small molecule in the complex matrix of filtered undiluted blood serum. Its uncomplicated construction and compact size, together with the remarkable performances, represent a leap forward toward effective point-of-care devices for therapeutic drug concentration monitoring.

Characterization of effective mobility by split C(V) technique in N-MOSFETs with ultra-thin gate oxides

Reliable split C(V) measurements are shown to be feasible on ultra-thin oxides (down to 1.2 nm) by using relatively small area MOSFETs (typically 100 mum(2)). To this end, specific correction procedures for parasitic parallel capacitances and gate leakage impact on source-drain current characteristics are proposed. The amplitude of the effective mobility is found to be degraded significantly with oxide scaling. Moreover, the mobility attenuation at high field associated to the surface roughness remains unchanged with oxide thickness reduction. This mobility degradation could find its origin in enhanced remote coulomb or interface plasmon-phonon scattering processes, which are reinforced by oxide thinning

Microelectrodes on a Silicon Chip for Label-Free Capacitive DNA Sensing

This paper presents the experimental characterization of two-terminal microfabricated capacitors for microarrays with an electrical sensing of label-free deoxyribonucleic acid (DNA). So far, such a concept has been demonstrated only in experimental setups featuring dimensions much larger than those typical of microfabrication. Therefore, this paper investigates: 1) the compatibility of the silicon microelectronic processes with biological functionalization procedures; 2) the effects of parasitics when electrodes have realistic dimensions; 3) measurement stability and reproducibility; and 4) the possibility of a fully integrated stand-alone device. The obtained results clearly indicate that two-terminal capacitive sensing with fully integrated electronics represents a viable technology for a DNA label-free detection/recognition

A Biosensor for Direct Detection of DNA Sequences Based on Capacitance Measurements

The large demand for DNA analysis calls for the development of portable, low-cost, easy-to-perform assays. We developed and performed preliminary assessments of an integrable biosensor for the direct detection of DNA sequences through capacitance measurements. The device behaves consistently with a proposed electrical model and it reliably detects DNA hybridization with high specificity. We have also verified the reproducibility of the experimental results and the reusability of the DNA biosensor.