In-situ thermal annealing of on-membrane silicon-on-insulator semiconductor-based devices after high gamma dose irradiation.

In this paper, we investigate the recovery of some semiconductor-based components, such as N/P-type field-effect transistors (FETs) and a complementary metal-oxide-semiconductor (CMOS) inverter, after being exposed to a high total dose of gamma ray radiation. The employed method consists mainly of a rapid, low power and in situ annealing mitigation technique by silicon-on-insulator micro-hotplates. Due to the ionizing effect of the gamma irradiation, the threshold voltages showed an average shift of -580 mV for N-channel transistors, and -360 mV for P-MOSFETs. A 4 min double-cycle annealing of components with a heater temperature up to 465 °C, corresponding to a maximum power of 38 mW, ensured partial recovery but was not sufficient for full recovery. The degradation was completely recovered after the use of a built-in high temperature annealing process, up to 975 °C for 8 min corresponding to a maximum power of 112 mW, which restored the normal operating characteristics for all devices after their irradiation.

Lytic enzymes as selectivity means for label-free, microfluidic and impedimetric detection of whole-cell bacteria using ALD-Al2O3 passivated microelectrodes.

Point-of-care (PoC) diagnostics for bacterial detection offer tremendous prospects for public health care improvement. However, such tools require the complex combination of the following performances: rapidity, selectivity, sensitivity, miniaturization and affordability. To meet these specifications, this paper presents a new selectivity method involving lysostaphin together with a CMOS-compatible impedance sensor for genus-specific bacterial detection. The method enables the sample matrix to be directly flown on the polydopamine-covered sensor surface without any pre-treatment, and considerably reduces the background noise. Experimental proof-of-concept, explored by simulations and confirmed through a setup combining simultaneous optical and electrical real-time monitoring, illustrates the selective and capacitive detection of Staphylococcus epidermidis in synthetic urine also containing Enterococcus faecium. While providing capabilities for miniaturization and system integration thanks to CMOS compatibility, the sensors show a detection limit of ca. 10(8) (CFU/mL).min in a 1.5 µL microfluidic chamber with an additional setup time of 50 min. The potentials, advantages and limitations of the method are also discussed.

Assessment of different functionalization methods for grafting a protein to an alumina-covered biosensor.

The specificity of biosensors is typically obtained by surface biofunctionalization, which enables the selective binding of biomolecules. This critical step is sensitive to the nature of materials and to the overall experimental conditions. Here, we provide a comprehensive study of several biofunctionalization methods, including the layer-by-layer technique and both the gas-phase and liquid-phase silanizations, and we propose a new maleimide-based protocol for grafting a protein to a sensor covered by alumina. This method was then validated by making a respiratory syncitial virus-specific biosensor.

Electrical detection of DNA hybridization: three extraction techniques based on interdigitated Al/Al2O3 capacitors.

Based on interdigitated aluminum electrodes covered with Al(2)O(3) and silver precipitation via biotin-antibody coupled gold nano-labels as signal enhancement, three complementary electrical methods were used and compared to detect the hybridization of target DNA for concentrations down to the 50 pM of a PCR product from cytochrome P450 2b2 gene. Human hepatic cytochrome P450 (CYP) enzymes participate in detoxification metabolism of xenobiotics. Therefore, determination of mutational status of P450 gene in a patient could have a significant impact on the choice of a medical treatment. Our three electrical extraction procedures are performed on the same interdigitated capacitive sensor lying on a passivated silicon substrate and consist in the measurement of respectively the low-frequency inter-electrodes capacitance, the high-frequency self-resonance frequency, and the equivalent MOS capacitance between the short-circuited electrodes and the backside metallization of the silicon substrate. This study is the first of its kind as it opens the way for correlation studies and noise reduction techniques based on multiple electrical measurements of the same DNA hybridization event with a single sensor.

Comparison of DNA detection methods using nanoparticles and silver enhancement.

DNA microarrays are an emerging technology for the parallel detection of DNA molecules. Fluorescent molecules are the current standard for a DNA array's optical readout but they possess some drawbacks including the stability of the dyes and the cost of the scanners. Therefore alternative labelling strategies are of considerable interests. One such strategy is the use of nanoparticles which offers several advantages in terms of stability and versatility of the detection mode. The authors present a review on the different ways DNA can be detected, mainly onto a solid support, using nanoparticle labels.