Lead by the results of our previous work, in which we designed the sweat glands prototype according to AM (Advanced Manufacturing) requirements, in this study we aimed to integrate the previously manufactured channels into a stereolithography (SLA)-manufactured module, in order to avoid support structures inside the channels and the model cavities. That was achieved by distributing the channels in the manner which approximates the sweat glands distribution on an equivalent real body part and to be able toadjust the sweat quantity, to the estimated sweat rates found in the literature. The manufactured module has integrated humidity and temperature sensors, which will allow an accurate quantitative assessmentof the thermoregulation of the individual modules and the sweat glands prototype as a whole.

A three dimensional, additively manufactured interdigital capacitive sensor for fluid level measurement applications is introduced. The device was fabricated using the fused filament fabrication (FFF) additive manufacturing (AM) process and an off the shelf conductive filament with a volume resistivity ρ = 0.6 Ω cm. The 3D fabrication process allows great flexibility in terms of sensor ̇ design and an increase of the surface area between the electrodes, compensating the relatively large plate separation and yielding a high sensitivity to increasing fluid levels. The measurements presented in this abstract show the average increase of capacitance in response to an incrementally increasing volume of de-ionized water (DI-water) filled between the separate digits.

In this contribution, we present a symmetric arrangement of electromagnetically actuated, resonating plates for viscosity and density measurement. Regarding the oscillation mode, the design resembles a tuning fork and is based on previously introduced resonating plate designs. It exhibits similar sensitivity to viscosity as previously characterized single plate resonators, while having two shear modes at different frequencies, that can be both actuated with the same setup allowing a multi-frequency analysis of viscoelastic liquids. We introduce the new design and present the results of FE simulations in order to determine the associated eigenmodes. We investigate the effects of the actuation method on the sensors performance by actuating with two different magnetic field configurations and by trying different configurations of the actuation and readout circuit, from which we show that with a particular configuration, Q-factors of up to 5000 can be reached for the symmetric shear mode. From these results we then proceed to suggesting a simplified lumped mechanical oscillator model explaining the dependence of the resonator’s Q-factor while operated in air on induced eddy currents damping. Measurement results are presented which show the general dependence of the new design’s actuated modes, the anti-symmetric and symmetric mode, on viscosity and density. We apply two different models to our data: a newly developed generalized model and a simplified version of that model which better describes the observed relation of our measurements to the square root of the product viscosity density. We then proceed to perform an estimated error analysis on viscosity, density, and the square root of their products based on the above mentioned applied models. From this error analysis several conclusions are drawn, mainly that the symmetric mode is more accurate than the anti-symmetric one, the sensor is generally more accurate for lower viscosity liquids, and lastly that the square root of the viscosity density product is a more suited value for the description of the sensor's behavior than the viscosity or the density alone.

The synovial fluid is found in joints of vertebrates and contains a high molecular weight polysaccharide (hyaluronan) acting as a modifier to ensure proper lubrication. Both, its concentration and molecular weight are subject to pathological alterations in certain diseases. Laboratory analysis of physical properties is difficult because of the limited amount of sample volume (usually below 100 mu l). We present a sensor platform which requires volumes below 10 mu l to measure the viscoelastic properties in the kilohertz range and the electrochemical impedance spectrum (EIS) from 10(2) to 10(6) Hz. Two electrodynamic acoustic shear wave transducers are used to measure both the single-sided viscoelastic shear impedance and the transmission of shear waves. The same elements are used as electrodes for measuring the EIS with a precision impedance analyser. The device is supposed to be used for clinical diagnosis and therapy tracking. (C) 2015 The Authors. Published by Elsevier Ltd.

We introduce a resonating viscosity-density sensor array measurement setup for the characterization of synovial fluid, the joint-lubricant in humans and animals, in an isolated and protective environment to prevent degradation of the fluid sample due to exposure to air. Our measurement technique requires very low sample volumes of 28 μl or less, and offers a more reliable alternative to capillary breakup tests already in use. The described method can be extended to characterize other biological and non-Newtonian fluids.

Hitherto zeolite formation has not been fully understood. Although electrochemical impedance spectroscopy has proven to be a versatile tool for characterizing ionic solutions, it was never used for monitoring zeolite growth. We show here that EIS can quantitatively monitor zeolite formation, especially during crucial early steps where other methods fall short.

We present a pressure-wave-based acoustic sensor device for inline monitoring of polymer flow behavior. The device is made to be integrated in a slit capillary of an in-line-extrusion-rheometer, but could be implemented in any die used for extrusion. It was manufactured to withstand the high pressures involved in the extrusion process by employing a boundary reflection based acoustic measurement to determine the viscosity of the polymer. A high temperature graded PZT disc transducer was used and the whole system was designed to measure viscosities at the temperatures of the extruder without the need for external cooling of the PZT element.

We introduce a wide channel, micro-fluidic device for the transfer of particles and cells between different fluidic media, for example from a sample liquid to water, based on acoustophoresis (AP) as well as negative dielectrophoresis (nDEP). Rapid prototyping was used in order to determine the dimensions of the microfluidic channels and FE (finite element) simulations were performed to derive the optimal nDEP electrodes geometries. We chose to combine nDEP and AP because of the selective nature of DEP and the high throughput possibilities that the AP offers as well as the AP independence from the dielectric properties of the used media.

The performance of a recently introduced method to estimate the resonance parameters from complex spectral data and the error propagation for viscosity and density parameters of liquids are examined. The method is known to produce excellent results when used for piezoelectric and Lorentz force actuated sensors for single port or two-port devices. The method is also suited for very low quality factors (< 10) which extends the usable measurement range of many sensor concepts, especially for fluid sensing applications. Generally valid expressions for the measurement accuracy are stated and compared to measurement results obtained with a piezoelectric tuning fork and a Lorentz force actuated and inductively read out platelet sensor.

We present a novel sensor design for viscosity measurements using shear-waves, which opens up opportunities for rheological applications in the low kHz range. Two electrodynamic in-plane plate resonators are aligned in parallel and separated by a defined gap filled with the fluid sample. The lower plate is actuated, generating a shear-wave in the viscous or viscoelastic fluid. The response on the upper plate, which is coupled to the lower plate with the viscous fluid in between, is recorded in a frequency range where resonances are observed. The coupling of both resonators increases with viscosity, allowing a, for resonator sensors unprecedented, high viscosity measurement range measured up to 17.1 Pa.s. In this contribution we will introduce the sensor concept, present an analytical model and discuss the results of measurements made with various fluids.

The principle of using steel tuning forks for viscosity and mass density measurements is investigated. From recorded frequency responses of fully immersed tuning forks, resonance frequencies and quality factors are evaluated and related to the liquids mass densities and viscosities. The benefit of these resonators is their mechanical rigidity which allows the application in harsh environments and mechanical cleaning processes without detuning or damaging the device. The setup was particularly devised that only the resonator itself but no excitation or read-out mechanisms get wetted by the sample liquid. The results obtained with a circular cross-sectioned tuning fork in different liquids are shown and discussed.

In this contribution, U-shaped resonators used for viscosity and mass density sensing are presented. These devices were especially designed to reduce and overcome spurious instabilities, which were observed in previous sensor designs. Five sensor designs are presented and their sensitivities to viscosity and mass density are examined. The setups are discussed regarding their working principle, sensitivity, cross-sensitivity to temperature and repeatability. The measurement results in liquids featuring different viscosities and mass densities are shown and the theory necessary to relate the measured data to viscosity and mass density is outlined.

In this contribution a concept study for an electrody-namically driven and read-out torsional oscillator is presented. The fundamental mechanical and electrodynamical theory is explained in detail and measurements results obtained with first prototypes are discussed.

Miniaturized resonating viscosity sensors operating at frequencies in the low KHz-range, offer portability and measurement results comparable to existing lab viscometers. In this paper, we present a viscosity measurement cell, based on a concept that we proposed earlier utilizing electrodynamic-acoustic resonator sensors, with a novel design based on interchangeable resonator cards. Experimental results obtained with the new resonator cards show the dependence of the resonance frequency and Q-factor on viscosity. We obtained repeatability errors in the order of a few percent for a range of Newtonian liquids. We discuss the related errors in viscosity measurement based on deviations in the determination of the Q-factor and resonance frequency. In addition, experiments were made aiming at increasing the initial Q-factor of the sensor by varying the distance separating the two magnets of the viscosity measurement cell and investigating different bonding techniques of the resonator card. Based on these results, design rules for the magnetic circuit and the mounting are derived. (C) 2013 Elsevier B.V. All rights reserved.

Miniaturized resonating viscosity sensors operating at frequencies in the low KHz-range offer portability and results comparable to existing lab viscometers. In this paper we will briefly describe a viscosity measurement cell based on a concept that we proposed earlier utilizing electrodynamic-acoustic resonator sensors with a design based on interchangeable resonator cards, which allow for ease of maintenance of the device and provides higher measurement repeatability. Experimental results obtained with the new resonator cards show the clear dependence of the resonance frequency and Q factor on viscosity. In addition, an experimental approach is taken to study the effects of magnetic field variations on the Q factor of the investigated resonators which are suspended by S-shaped (meander) beams and operating either in air or liquids.

This contribution discusses the influence of the magnetic flux density on Lorentz force driven resonant sensors. A closed form model describing the physical behavior of the resonating wire shows the quadratic influence of magnetic flux density on the readout signal, which in our case is the motion induced voltage in the oscillating wire. It is furthermore shown that the resonating wire sensor is well suited for magnetic field measurements, even at high temperatures.