Electrocardiography (ECG) is one of the most widely used diagnostic methods to examine the development of cardiovascular diseases (CVD). It is important to have a long-term continuous ECG recording to properly monitor the heart activity, which can be measured by placing two or more electrodes on the skin. Ag/AgCl gelled electrodes are often used for the ECG measurement, but they are not suitable for long-term monitoring due to the dehydration of the gel over time and skin irritation. Textile-based electrodes could have an important role in replacing the gelled electrodes and avoid their associated problems. This paper focuses on the development of a textile-based electrode and studying its ECG detecting performance. We developed silver printed textile electrodes via a flat-screen printing of silver ink on knitted polyester fabric. The surface resistance of silver-coated PET fabric was 1.78 Ω/sq and 3.77 Ω/sq before and after washing, respectively. Stretching of the conductive fabric from 5% to 40% caused a 6% to 18.28% increase in surface resistance. The silver-printed PET fabric stayed reasonably conductive after washing and stretching which makes it suitable for wearable applications. Moreover, the ECG measurement at static condition showed that the signal quality collected before and after washing were comparable with the Ag/AgCl standard electrodes. The P, QRS, T waveforms, and heartbeat before washing in respective order were 0.09 mV, 1.20 mV, 0.30 mV for the silver printed fabric electrode and 72 bpm, and 0.10 mV, 1.21 mV, 0.30 mV, and 76 bpm for Ag/AgCl standard electrode.

Carbon particle-filled elastomers are a widely researched option to be used as piezoresistive strain sensors for soft robotics or human motion monitoring. Therefore, various polymers can be compounded with carbon black, carbon nano tubes (CNT) or graphene. However, in many studies the electrical resistance’s strain response of the carbon-particle filled elastomers is non-monotonic in dynamic evaluation scenarios. The non-monotonic material behavior is also called shoulder phenomenon or secondary peak. Until today, the underlying cause is not sufficiently well understood. In this study, several influencing test parameters on the shoulder phenomena are explored like strain level, strain rate and strain history. Moreover, material parameters like CNT content and anisotropy are varied in melt-spun CNT filled thermoplastic polyurethane filament yarns and their non-monotonic sensor response is evaluated. Additionally, a theoretical concept for the underlying mechanism and thereupon-based model is developed. An equivalent circuit model is used, which incorporates the visco-elastic properties and the characteristic of the percolation network formed by the conductive filler material. The simulation results are in good agreement when compared to the experimental results.

The study of eating behavior has become increasingly important due to the alarming high prevalence of lifestyle related chronic diseases. In this study, we investigated the feasibility of automatic detection of eating events using affordable consumer wearable devices, including Fitbit wristbands, Mi Bands, and FreeStyle Libre continuous glucose monitor (CGM). Random forest and XGBoost were applied to develop binary classifiers for distinguishing eating and non-eating events. Our results showed that the proposed method can recognize eating events with an average sensitivity of up to 71%. The classifier using random forest with SMOTE resampling exhibited the best overall performance.

Stacks consisting of titanium, platinum, and gold layers constitute a popular metallization system for the bond pads of semiconductor chips. Wire bonding on such layer stacks at different temperatures has extensively been investigated in the past. However, reliable information on the bondability of this metallization system after a high-temperature sintering process is still missing. When performing wire bonding after pressure sintering at, e.g., 875 °C, bonding failures may occur that have to be identified and analyzed. In the present study, focused ion beam (FIB), scanning electron microscopy (SEM), and elemental mapping are utilized to characterize the root cause of failure. As probable root cause, infusion of metallization layers is found which causes an agglomerate formation at the interface of approximately 2 micron height difference on strain gauge contact pads and possibly an inhomogeneous mixing of layers as a consequence of the high-temperature sintering process. Potential treatment to tackle this agglomeration with the removal of above mentioned height difference during the process of contact pad structuring and alternative electrical interconnect methodologies are hereby suggested in this paper.

Federated learning is a knowledge transmission and training process that occuring in turn between user models at edge devices and the training model at the central server. Due to privacy policies, concerns and heterogeneous data, this is a widespread requirement in federated learning applications. In this work, we use knowledge-based methods and in particular case-based reasoning (CBR) to develop a wearable explainable artificial intelligence (xAI) framework. CBR is a problem-solving AI approach for knowledge representation and manipulation which considers successful solutions of past conditions that are likely to serve as candidate solutions for a requested problem. It enables federated learning when each user owns not only his/her private data, but also uniquely designed cases. New generated cases can be compared to the knowledge base and the recommendations enable the user to communicate better with the whole system. It improves users' task performance and increases user acceptability while they need explanations to understand why and how AI algorithms arrive at these solutions which is the best decision.

Monitoring of intracellular pH changes in situ can provide valuable information about cellular metabolism and a deeper understanding of physiological processes. Most traditional fluorescent indicators are only capable of a relative assessment of changes in the studied parameter in the cell. We associate the possibility of measuring the absolute values that characterize the analyte with the detection of the indicator signal in the time domain, where its quantitative measure is the fluorescence lifetime (tau). In this project, we are testing promising pH-sensitive fluorophores with labile fluorescence lifetimes-EYFP-G65T and EGFP-Y145L/S205V– both as fluorescent core for the previously described pH indicators and as independent pH indicators. Measurement of the fluorescence attenuation kinetics of four structures (EYFP-G65T, EGFP-Y145L/S205V, SypHer3s, and SypHer3s-G65T) over a wide pH range revealed areas where tau is linearly dependent on pH. The differences in the fluorescence excitation modes of these molecules makes it possible to use them in one experimental system to assess pH changes in a wide range 4.0–9.0. We showed that under the conditions of traditional fluorescence microscopy (in the cytoplasm of HEK293 cells), the SypHer3s-G65T indicator shows a dynamic response range approximately 3 times wider than the original SypHer3s.

Transformer-type inductive conductivity sensors (TICS) are the industry standard for long-term conductivity measurement in fluids. This paper analyzes the potential of TICS as a low-cost alternative to the more cost-efficient type of conductivity cells by an implementation with reduced complexity. Sensor characteristics and performance in comparison to high precision sensor are described in the study. Linearity and hysteresis error in measurement, reproducibility and permeability influence by the temperature change are quantified through the experiments. The results were interpreted in regards to core material, geometric properties and noise shielding. Study presented in this paper provides a better understanding of performance and uncertainty characteristics in order to improve the design of low-cost transformer type inductive conductivity sensors.

Wireless capsule endoscopy is a promising and less invasive alternative to conventional endoscopy. A patient swallows a small capsule with an integrated camera to capture a video of the gastrointestinal tract. For accurate diagnosis and therapy, the capsule position in terms of the travelled distance must be known for each video frame. However, up to now, there is no reliable localization method for endoscopy capsules. In this paper, a novel magnetic localization method is proposed. A coil as a magnetic field source is integrated into a capsule and fed with a low-frequency alternating current to prevent static geomagnetic field interference. This alternating magnetic field is measured by twelve magnetic sensors arranged in rings around the abdomen. The coil and the capsule batteries were designed based on the geometry and power supply of a commercially available endoscopy capsule and simulated by COMSOL Multiphysics software. In this way, the coil position and orientation were determined with an accuracy below 1 mm and 1°, respectively. As an analytic model for the magnetic flux density of the coil in that setup, a modified dipole model was derived. It was used to show that the batteries help to increase the amplitude of the magnetic flux density. The model is valid when signals below 100 Hz are applied, and no eddy currents are generated within the batteries. It is concluded that the magnetic flux density generated by the developed coil would be measurable with state-of-the-art magnetic sensors.

In this paper, we investigate the efficient structure for point-of-care (POC) molecular diagnostic system based on of the industrial-internet-of-things (IIoT). The target system can perform automated molecular diagnosis including DNA extraction, PCR amplification, and fluorescence detection. Samples and reagents are placed in a multi-room cartridge and loaded into the system. A rotating motor and a syringe motor control the cartridge to extract DNA from the sample. The extracted DNA is transferred to a polymerase chain reaction (PCR) chamber for DNA amplification and detection. The proposed system provides multiplexing of up to 4 colors. For POC molecular diagnostics, World Health Organization demands features such as low volume, low cost, fast results, and user-friendly interface. In this paper, we propose a system structure that can satisfy these requirements by using PCR chip and open platform. A distributed structure is adopted for the convenience of maintenance, and a web-based GUI is adopted for the user’s convenience. We also investigated communication problems that may occur between system components. Using the proposed structure, the user can conveniently control from standard computing devices including a smartphone.

Additive Manufacturing (AM) also known as 3D-printing comprise a group of versatile technologies that has been used in electrochemistry last years. Among the 3D-printing technologies, Fused Deposition Modelling (FDM) highlights in the fabrication of reliable portable point of need platforms for its rapid prototyping, low cost, design customization, and ease of integration of diverse components as microfluidics, and electrodes. This work propose the electrochemical and hydrodynamic characterization of a novel 3D-printed flow-cell integrated with removable commercial-available screen-printed carbon electrodes. Integration of flow-cell and electrodes resulted in the proposed 3D-printed electrochemical flow-cell adjustable and customizable to detect any desired biomarker. The 3D-printed flow cell was fabricated through FDM and the ESCARGOT (Embedded SCAffold RemovinG Open Technology) protocol. Electrochemical and hydrodynamic characterization comprised an experimental and a computational model study respectively, with the purpose to choose the best working flow rate and to understand the behavior of the fluid through the device. Experimental study was carried out running cyclic voltammetries of [Fe (CN)₆]^4−/3− redox probe at different flow rates (0, 50, 100, 200, 300, 400, 500 and 1000 μL min⁻¹) and the hydrodynamic computational model was performed using COMSOL Multiphysics 5.3a setting physics for laminar flow and transport of diluted species at the same flow rates. Results indicated that the best working flow rate was 50 μL min⁻¹, and recirculation and vortices zones are formed at flow rates higher than 200 μL min⁻¹.