When performing vibration-based measurement techniques e.g., for Structural Health Monitoring, piezo-electric elements are often used as sensor and/or actuator part due to their durability. The connection between the piezo-electric element and the test structure plays a decisive role for the quality of the results obtained in the vibration-based measurement process. In addition to stable and mode-independent vibration transmission, further requirements such as reversibility or temperature resistance can be imposed depending on the application. In many preliminary studies, especially bonding by means of a two-component epoxy resin was practically and simulatively validated for a high amount of use cases. Nevertheless, the limited reversibility and the preparation time of the adhesion process can limit the flexibility of the vibration-based measurement method. The aim of this work is to evaluate different joining technologies of piezo-electric elements on metal and polymer substrates with special respect to reversibility. Different techniques for joining piezo elements are collected considering previous work as well as newly developed approaches within the scope of the work. In the next step, frequency spectra of simple circular blanks are obtained using an EMI-setup from piezo elements joined to the blanks with the appropriate joining technique. Joining by means of a two-component epoxy is considered as the reference method. All joining techniques are evaluated especially based on degree of reversibility, transmission quality, effort for implementation and durability in comparison to the reference method. Finally, recommendations regarding the proper joining technique for different experimental conditions will be given based on the results.

The dielectric parameters help in understanding the structural, compositional and functional analysis of biological samples. These parameters have also been widely adopted in biomedical and therapeutic fields. In the microwave region, these parameters carry much interest because the principal constituent of most biological cells is water. Therefore, it is difficult to isolate the dielectric response of water present in a biological-composite. So, the technique with enhanced sensitivity is essential for measuring the dielectric properties of biological samples. In this paper, we report the design and CST simulation of a 2D-planar patch type antenna with capacitive coupling introduced by dividing the patch through a gap. The aforementioned design further improves the antenna’s sensitivity towards the dielectric properties of materials. Here, we simulated ten biological phantoms by measuring the shift in resonant frequency and return loss. Our results were identical when loading samples on either of the two introduced patches. These results suggest the repeatability and further improvements in a cavity-based technique where the sample localization is an important issue. Moreover, we analytically studied the dependency of gain and directivity of the antenna on the capacitive coupling, which plays a major role in the antenna’s sensitivity towards dielectric characterization.

Flexible pressure sensor array can be as tactile sensor array to detect loading pressures and locations in lots of applications, including wearable devices, electronic skins, robotics, and machine learning. Many studies have been proposed high performance flexible tactile sensor array. However, when the sensing points and spatial resolution increase, signal wiring issue arises, but the cumbersome I/O wirings between sensors and readers will greatly affect the user’s mobility and comfort. Recently, several methods have been proposed to simplify the signal line. Some common approaches utilize orthogonal electrodes to reduce I/O ports from 2n² to 2n in an n × n array. Some innovative methods can reduce I/O ports to 2 in an n × n array, but they are unable to perform multi-touch measurement and maintain high spatial resolution at the same time. To achieve multi-touch and high spatial resolution, this research proposes a flexible pressure sensor array is based on parallel RLC resonance circuit and made by PDMS/Graphene mixture as piezoresistive sensor on FPC (Flexible Printed Circuit). In this research, Single pressure sensor can measure the pressure from 37.5 to 250 kPa. Loading multi-points force on the pressure sensor array, it can distinguish different pressure with different loading force on sensor array. The results of the hardness experiment show pressure distribution of hard ball on pressure sensor array is one to two pixels, and soft ball is three to nine pixels by loading force 1.5, 2.7, and 3.9 N. This design successfully distinguishes different hardness, and it is potential to be applied in electronic skin and wearable device.

Digital (droplet-based) microfluidic platform has become an attractive approach for biomedical applications, such as immunoassay, because it requires less sample volume and take shorter time in bio-reaction. However, the digital microfluidic immunoassay based on electrowetting technology often has dielectric breakdown problem due to biofouling and high input voltage. Here a highly reliable mechanical digital microfluidics immunoassay is reported by combining the movable-chip design and the glass microspheres as the carrier of antibody. Since the droplet movement is achieved by moving the chip in the mechanical digital microfluidic system, high voltage is not required, the biofouling won’t cause any problem in droplet movement during the process of immunoassay. In addition, owing to the buoyancy, the glass microspheres can self-concentrate to the top of droplet, which helps to improve the detection sensitivity and reduce the limit of detection. The Human IL-1β is used here to demonstrate the performance of the proposed mechanical digital microfluidic immunoassay. It is shown that the limit of detection is 0.246 pg/mL, required sample volume is only 2 μL, and the time for immunoassay process is less than 30 min. which is similar to our previous digital microfluidics immunoassay based on electrowetting technology with much better reliability.

This article presents aspects related to the protection with a double shield, made of stainless steel, of a robot for emergency situations against the effect of flames due to a fire. The ground robot is semi-autonomous / autonomous, with a wheeled propeller (6x6). The robot, designed and built at TRL 2 level, is intended for fire investigation, monitoring and intervention, in particular for petrochemical plants. The role of the shield is to protect the equipment that is part of the robot, such as: controllers, sensors, communications, power supply, etc. The need to mount a thermal protection shield on the intervention robot was given by the fact that fires at petrochemical plants generate very large thermal fields and gradients, which on the one hand are responsible for creating blind spots. These blind spots do not allow intervention crews to see what is happening in that area. These blind spots are characterized by very high temperatures. The dynamics of fires is unpredictable, therefore, to analyse the performance of the heat shield, we will perform a numerical-experimental analysis.

The measurement of the ground reaction forces (GRFs) helps in determining the role of each limb for support and propulsion, in predicting muscle activities, and in determining the strain conditions experienced by bones. Measuring the GRFs in mice models is therefore a cornerstone for understanding the rodent musculoskeletal and neuromotor systems, as well as for improved translation of knowledge to humans. Current force plates are too big in size to allow the measurement of forces for each paw. This limitation is mainly due to the large size of the used sensors. The goal of our study was therefore to develop a small 3D force sensor for application in rodent gait analysis. We designed a flexible and small mechanical structure (8 mm × 8 mm) to isolate force components. Using FEM simulation, we chose the area with the highest strain to fix two strain gauges for each direction. The small size of the sensor allows us to fix four of them under a plate on the mouse paw size (approximately 17 mm). According to our primarily results the force plate has a resolution of 2mN in the vertical direction and 1mN in the fore-aft and mediolateral directions. The construction of a runway with such a force plate will allow the measurement of GRFs and the center of pressure of each rodent paw for different steps. Such techniques thus provide a basis for assessing functionality in mice models, towards improved translation of rodent research.

A concept of virtual sensor array based on electrically controlled variation of affinity properties of the receptor layer was realized on the base of integrated electrochemical chemotransistor containing conducting polymer as the receptor layer. An electrical control of the redox-state of the polymer (polyaniline) was performed in five-electrode configuration with four electrodes for conductivity measurements and Ag/AgCl reference electrode integrated on the same glass chip. Using an ionic liquid was provided electrical connection between the reference electrode and chemosensitive material. Conductivity measurements demonstrated potential controlled electrochemical conversions of the receptor material between different redox-states. Binding of trimethylamine at three different potentials, corresponding to these states was studied. The results demonstrated that both kinetic- and equilibrium binding properties of the receptor are controlled by electrical potential thus providing a possibility to form a virtual sensor array using only a single sensing element. The concept was applied for monitoring of fish headspace. Using three characteristics of the sensor response measured at three different redox states of the same sensor material, we have obtained signals from a virtual sensor array consisting of nine chemosensitive elements. The sensor displays systematic changes of its nine signals during fish degradation. This approach can be applied also for the electrical control of affinity of immunoglobulins. A development of a new materials with conducting electrically controlled affinity is in progress.

The paper presents a portable passwords manager having a two stages biometric based access procedure. Data security using biometric methods was chosen as a variant of reduced complexity, but very effective in preventing cyber theft. The implementation of biometrics for the purpose of identification in high security systems has become a must with the evolution of technology and the spike in identity theft. Unlike, passwords or IDs, a biometric feature is an identifier that can not be lost, stolen or replicated, fact that offers biometric authentication systems an increased level of security. During the first accessing step, the 3DPassManager portable device measures heartbeat and uses fingerprint and iris features to realize a unique biometric based authentication. While the specific characteristics of fingerprint and iris are integrated to ensure that the person using the device is the rightful owner, the pulse is utilized to verify if possible previously acquired static images are not used. During the second accessing step, a password is generated based on fingerprint details, being valid only for a small time interval. The fingerprint is stored in a 1024-bit long key. Once the access is allowed, the passwords will be available trough an extension installed on the web browser. The device has the size of a cigarette pack and communicates with the PC by scanning a QR code. It is safe and was tested for dictionary and brute force attacks.

Carrier mobilities and concentrations were measured for different p- and n-type silicon materials in the temperature range 0.3–300 K. Simulations show that experimentally determined carrier mobilities are best described in this temperature range by Klaassen´s model. Freeze out reduce the carrier concentration with decreasing temperature. Freeze out, however, depends on the dopant type and initial concentration. Semi-classical calculations are useful only for temperatures above 100 K. Otherwise quantum mechanical calculations are required.

The rapid prototyping of low cost sensors is assuming a strategic importance in several application fields. In this paper a fully inkjet printed mass sensor is proposed. The device consists of a PET (poly-ethylene terephthalate) cantilever beam, which is driven to its resonant mode by an electromagnetic actuation mechanism, implemented through the interaction between a current impulse flowing through a planar coil (inkjet printed on the PET beam), and a permanent magnet, facing the actuation coil. Target masses are positioned close to the beam end. The sensing methodology, based on the relationship between the beam first natural frequency and the target mass, is implemented through a Strain Gauge (inkjet printed across the fixed end of the cantilever). The resonant operating mode of the sensor confers intrinsic robustness against instabilities of the strain sensor structure (e.g., the residual stress of the cantilever beam), the target mass material and the magnet-coil distance. The latter indeed changes as a function of the target mass values. The friction-less actuation mode is another shortcoming of the sensor, as well as the low cost feature arising from the adopted technology. As far as we know, the solution proposed is the first example of a low cost fully printed mass sensor. The operating range of the device is 0–0.36 g while its resolution is in the order of 1.0 mg, thus addressing crucial application fields. A Q factor around 35 has been estimated, which confirms the suitable performances of the sensor in term of selectivity and resolution.