Bernd Henning

Bio: Bernd Henning is an academic researcher from University of Paderborn. The author has contributed to research in topics: Ultrasonic sensor & Transducer. The author has an hindex of 14, co-authored 112 publications receiving 867 citations. Previous affiliations of Bernd Henning include University of Freiburg & Otto-von-Guericke University Magdeburg.

SPICE model for lossy piezoceramic transducers

Abstract: A transmission line equivalent circuit for piezoelectric transducers has been modified to provide modeling of lossy piezoceramic transducers. A lossy transmission line is used to model the mechanical losses. The equivalent circuit parameters are derived from analogies between electrical transmission lines and acoustic wave propagation. Implementation of the equivalent circuit model in SPICE is shown. Simulations and measurements in the time and frequency domain of a low-Q material and a multilayered ultrasonic sensor using a low-Q piezoceramic transducer are presented.

Ultrasonic sensors for process monitoring and chemical analysis: state-of-the-art and trends

Abstract: Ultrasonic sensors are used in a large variety of ways. New fields of ultrasonic: sensor and ultrasonic sensor system applications are process monitoring and control, automotive techniques and chemical analysis. These applications have enjoyed a rapid increase of interest in recent years. The development of new ultrasonic sensors or systems was and is essentially accelerated by the progress in electronics, by new piezoelectric materials, by exploitation of new technologies and by the need for new or more accurate analysis methods in many industrial branches. A review of ultrasonic sensors based on piezoelectric materials and resonators is presented. First, the physical background for ultrasonic wave propagation and corresponding technical applications is given. A definition of the ultrasonic sensor system is introduced later because an ultrasonic sensor alone makes no sense. For an efficient use of this sensor principle, a well-developed transmitter and receiver electronics and intelligent data-acquisition electronics are necessary. Secondly, it is shown that ultrasonic sensors can be divided into four groups depending on how the ultrasonic signal has been changed on its path during propagation or the transducer properties are changed by interaction with the surroundings. The present state of established sensors for flow, distance and level is discussed. Ultrasonic sensors for process monitoring are described. New application fields for these sensors can be predicted. Finally, ultrasonic microsensors are introduced. A description of their state-of-the-art and application examples are given. To conclude, the use of new technologies for the manufacture of miniaturized ultrasonic sensors and future developments are discussed.

Ultrasonic density sensor for liquids

Abstract: This paper presents an ultrasonic density sensor for liquids that unifies high accuracy with high durability and is suitable for on-line measurements in a wide range of tube diameters. The sensor consists of a transducer with a piezoceramic disk mounted between two reference rods of quartz glass. Additionally, a second transducer is used as a sound receiver. The density is obtained from the reflection coefficient of ultrasound at the interface between the quartz glass rod and the liquid and the transit time of sound between this interface and the second transducer. Parameters, such as high long-term stability and accuracy of /spl plusmn/0.1% of full scale, were obtained by an internal acoustic reference measurement. The reference signal is generated using the sound radiated from the rear side of the piezoceramic disk. Design aspects such as sensor materials and signal-to-noise ratio are discussed, and experimental results are given in this paper. Applications of the sensor include concentration measurement, and ultrasonic mass flow measurement.

2D phononic crystal sensor with normal incidence of sound

Abstract: The contribution presents the sensor application of a resonance-induced extraordinary transmission through a regular phononic crystal consisting of a metal plate with a periodic arrangement of holes in a square lattice at normal incidence of sound. The characteristic transmission peak has been found to strongly depend on sound velocity of the liquid the plate is immersed in. The respective peak maximum frequency can serve as measure for the concentration of a component in the liquid mixture, if a beneficial relation to the speed of sound of the liquid exists. Experimental verification has been performed with mixtures of water and propanol as model system. Here we especially pay attention to numerical calculations based on EFIT and COMSOL which reveal more insides to the wave propagation characteristics. Experimental investigations with Schlieren method and laser interferometry support the theoretical findings.

Cross-reactive chemical sensor arrays.

Abstract: Conventional approaches to chemical sensors have traditionally made use of a “lock-and-key” design, wherein a specific receptor is synthesized in order to strongly and highly selectively bind the analyte of interest.1-6 A related approach involves exploiting a general physicochemical effect selectively toward a single analyte, such as the use of the ionic effect in the construction of a pH electrode. In the first approach, selectivity is achieved through recognition of the analyte at the receptor site, and in the second, selectivity is achieved through the transduction process in which the method of detection dictates which species are sensed. Such approaches are appropriate when a specific target compound is to be identified in the presence of controlled backgrounds and interferences. However, this type of approach requires the synthesis of a separate, highly selective sensor for each analyte to be detected. In addition, this type of approach is not particularly useful for analyzing, classifying, or assigning human value judgments to the composition of complex vapor mixtures such as perfumes, beers, foods, mixtures of solvents, etc.

Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for Nucleic Acid Sensor Development

Abstract: The immobilization of two 30-mer oligonucleotides, one biotinylated (biotin-DNA) and the other having a mercaptohexyl group at the 5‘-phosphate end (BS1-SH), onto modified gold surfaces has been examined using a quartz crystal microbalance (QCM). Both single-layer and multilayer DNA films were prepared. The single-layer films of biotin-DNA were constructed by binding to a precursor layer of avidin, which had been attached to the QCM either covalently using a water-soluble carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) or via electrostatic interaction with poly(allylamine hydrochloride) (PAH). Single-layer films of BS1-SH were also formed on PAH via the electrostatic attraction between the amine groups on PAH and the negatively charged phosphate backbone of DNA. Multilayer films of DNA were fabricated by the successive deposition of avidin and poly(styrenesulfonate) (PSS), up to a total of nine avidin/PSS layers, followed by DNA adsorption. DNA immobilization and hybridization of the immob...

Sensors based on piezoelectric resonators

Abstract: A review of sensors based on piezoelectric crystal resonators is presented. The survey focuses on the fundamental resonator modes rather than on the variety of surrounding support configurations in special sensor applications. First, the general properties of vibrating crystal sensors and their inherent superiority are described. The sensor concepts utilizing either homogeneous resonators with temperature and pressure (stress) as primary measurants or composite resonators with areal mass density and viscoelastic properties of the 'foreign' layer as primary measurands are discriminated. A comparison between bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators with respect to their primary sensitivity functions and principal capabilities for sensor applications is given and the importance of recent investigations on Lamb wave and horizontal polarized shear wave (HPLW) interdigital transducer (IDT) resonators is acknowledged. The importance of mode purity for high dynamic range sensors based on resonators and some aspects of the demand on specialized electronics are emphasized. The present state of established sensors based on primary sensitivities, e.g., quartz-crystal thermometers, pressure transducers, thin-film thickness and deposition-rate monitors, viscoelastic layer analysers (crystal/liquid composite resonators) is reviewed. A selection of the most promising recently investigated vibrating crystal sensors utilizing indirect sensitivities is described, including the wide field of analyte-selective coatings and resonator-based immunosensors or immunoassays. Finally, the potential of alternative piezoelectric materials for future sensor developments is briefly discussed.

1. Ultrathin Multilayer Polyelectrolyte Films on Gold: Construction and Thickness Determination

Abstract: Thin organic films fabricated by the successive deposition of the polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) have been successfully grown up to 24 layers on gold surfaces. These films are formed via electrostatic attraction between adjacent layers of opposite charge. Their construction has been examined using a quartz crystal microbalance (QCM), reflection spectroscopy (RS), surface plasmon resonance (SPR), and X-ray photoelectron spectroscopy (XPS). The thickness of the multilayer assemblies increases with the number of adsorbed layers, although a linear increase is observed only after the deposition of four polyelectrolyte layers ((PAH/PSS)2). The (PAH/PSS)2 film facilitates regular, stepwise deposition of subsequent PAH and PSS layers. The thickness of (PAH/PSS)2 on gold was determined independently by QCM, SPR, and XPS to be 7.9 ± 0.6 nm. The PAH/PSS layer pair thickness after regular film growth was calculated to be 10.0 ± 0.8 nm. The formation of these thi...