Uwe Glaser

CMOS bridges and resistive transistor faults: IDDQ versus delay effects

Beyond the static stuck-at fault model, delay fault testing and static overcurrent testing have been suggested as approaches yielding reasonable fault coverage in CMOS circuits. Based on detailed simulations of resistive stuck-on-, stuck-open-, and bridging faults for typical CMOS circuits, this paper presents an analysis of their detectability and requirements for current and timing resolutions in overcurrent and delay fault testing.<<ETX>>

Detection of vancomycin resistances in enterococci within 3 ½ hours

Vancomycin resistant enterococci (VRE) constitute a challenging problem in health care institutions worldwide. Novel methods to rapidly identify resistances are highly required to ensure an early start of tailored therapy and to prevent further spread of the bacteria. Here, a spectroscopy-based rapid test is presented that reveals resistances of enterococci towards vancomycin within 3.5 hours. Without any specific knowledge on the strain, VRE can be recognized with high accuracy in two different enterococci species. By means of dielectrophoresis, bacteria are directly captured from dilute suspensions, making sample preparation very easy. Raman spectroscopic analysis of the trapped bacteria over a time span of two hours in absence and presence of antibiotics reveals characteristic differences in the molecular response of sensitive as well as resistant Enterococcus faecalis and Enterococcus faecium. Furthermore, the spectroscopic fingerprints provide an indication on the mechanisms of induced resistance in VRE.

Mixed Level Hierarchical Test Generation for Transition Faults and Overcurrent Related Defects

Automatic test pattern generation yielding high fault coverage also for non-trivial faults in CMOS circuits has found a wide attention in industry and research for a long time. Test generation from gate level netlists is quite efficient, but has shortcomings with respect to fault coverage in complex CMOS gates, while an approach relying on the transistor structure only is inefficient and virtually impossible for larger circuits. This paper describes mechanisms for coupling switch level and gate level test generation towards an efficient mixed level test generator that combines acceptable performance for large networks and high fault coverage also for non-trivial transistor networks. Patterns generated this way are inherently capable to detect interrupt-types of faults and transition faults. In combination with local overcurrent detectors, also stuck-on- and bridging faults can be identified.

Single cell analysis in native tissue: Quantification of the retinoid content of hepatic stellate cells

Hepatic stellate cells (HSCs) are retinoid storing cells in the liver: The retinoid content of those cells changes depending on nutrition and stress level. There are also differences with regard to a HSC’s anatomical position in the liver. Up to now, retinoid levels were only accessible from bulk measurements of tissue homogenates or cell extracts. Unfortunately, they do not account for the intercellular variability. Herein, Raman spectroscopy relying on excitation by the minimally destructive wavelength 785 nm is introduced for the assessment of the retinoid state of single HSCs in freshly isolated, unprocessed murine liver lobes. A quantitative estimation of the cellular retinoid content is derived. Implications of the retinoid content on hepatic health state are reported. The Raman-based results are integrated with histological assessments of the tissue samples. This spectroscopic approach enables single cell analysis regarding an important cellular feature in unharmed tissue.

Test generation for bridging faults in CMOS ICs based on current monitoring versus signal propagation

Bridge-type defects play a dominant role in state-of-the-art CMOS technologies. This paper describes a combined functional and overcurrent-based test generation approach for CMOS circuits, which is optionally based on layout information. Comparative results for benchmark circuits are given to demonstrate the feasibility of voltage-based versus IDDQ-based testing.

Simple Ciprofloxacin Resistance Test and Determination of Minimal Inhibitory Concentration within 2 h Using Raman Spectroscopy

Resistant bacteria are spreading worldwide, which makes fast antibiotic susceptibility testing and determination of the minimal inhibitory concentration (MIC) urgently necessary to select appropriate antibiotic therapy in time and, by this, improve patients outcome and, at the same time, avoid inappropriate treatment as well as the unnecessary use of broad spectrum antibiotics that would foster further spread of resistant bacteria. Here, a simple and fast Raman spectroscopy-based procedure is introduced to identify antimicrobial susceptibilities and determine the MIC within only 2 h total analysis, marking a huge time savings compared to established phenotypic methods nowadays used in diagnostics. Sample preparation is fast and easy as well as comparable to currently established tests. The use of a dielectrophoresis chip allows automated collection of the bacteria in a micron-sized region for high-quality Raman measurement directly from bacterial suspensions. The new Raman spectroscopic MIC test was validated with 13 clinical E. coli isolates that show a broad range of ciprofloxacin resistance levels and were collected from patients with blood-stream infection. Micro-Raman spectroscopy was able to detect ciprofloxacin-induced changes in E. coli after only 90 min interaction time. Principal component analysis as well as a simple computed ratio of the Raman marker bands at 1458 and 1485 cm-1 show a clear concentration-dependent effect. The MIC values determined with the new Raman method are in good agreement with MICs obtained by reference methods (broth microdilution, Vitek-2, E-test) and can be used to provide a classification as sensitive, intermediate, or resistant using the clinical breakpoints provided by EUCAST.

On-Chip spectroscopic assessment of microbial susceptibility to antibiotics within 3.5 hours.

In times of rising antibiotic resistances, there is a high need for fast, sensitive and specific methods to determine antibiotic susceptibilities of bacterial pathogens. Here, we present an integrated microfluidic device in which bacteria from diluted suspensions are captured in well-defined regions using on-chip dielectrophoresis and further analyzed in a label-free and non-destructive manner using Raman spectroscopy. Minimal sample preparation and automated sample processing ensure safe handling of infectious material with minimal hands-on time for the operator. Clinical applicability of the presented device is demonstrated by antibiotic susceptibility testing of Escherichia coli towards the commonly prescribed second generation fluoroquinolone ciprofloxacin. Ciprofloxacin resistant E. coli were differentiated from sensitive E. coli with high accuracy within roughly three hours total analysis time paving the way for future point-of-care devices. Spectral changes leading to the discrimination between sensitive and resistant bacteria are in excellent agreement with expected metabolic changes in the bacteria due to the mode of action of the drug. The robustness of the method was confirmed with experiments involving different chip devices with different designs, both electrode as well as microfluidics design, and material. Furthermore, general applicability was demonstrated with different operators over an extended time period of half a year.

Testability analysis for test generation in synchronous sequential circuits

Due to the complexity of test generation for stuck-at-faults in synchronous sequential circuits and the permanently increasing problem-size, algorithms solving this problem cannot work with acceptable CPU-time, even on computer systems with very high performance. Relating to this context this paper presents a new testability analysis guiding algorithms for sequential test generation. This testability analysis consists of two separated parts: First, a new technique for the detection of untestable stuck-at-faults; second, heuristics used to guide the decision process in test generation algorithms. Experimental results of sequential benchmark circuits allow us to conclude that our testability analysis provides less CPU-time for sequential test generation than other well-known testability analysis tools.<<ETX>>