Analog Interface Research Articles

Arterial Distension Monitoring Scheme Using FPGA-Based Inference Machine in Ultrasound Scanner Circuit System.

This paper presents an arterial distension monitoring scheme using a field-programmable gate array (FPGA)-based inference machine in an ultrasound scanner circuit system. An arterial distension monitoring requires a precise positioning of an ultrasound probe on an artery as a prerequisite. The proposed arterial distension monitoring scheme is based on a finite state machine that incorporates sequential support vector machines (SVMs) to assist in both coarse and fine adjustments of probe position. The SVMs sequentially perform recognitions of ultrasonic A-mode echo pattern for a human carotid artery. By employing sequential SVMs in combination with convolution and average pooling, the number of features for the inference machine is significantly reduced, resulting in less utilization of hardware resources in FPGA. The proposed arterial distension monitoring scheme was implemented in an FPGA (Artix7) with a resource utilization percentage less than 9.3%. To demonstrate the proposed scheme, we implemented a customized ultrasound scanner consisting of a single-element transducer, an FPGA, and analog interface circuits with discrete chips. In measurements, we set virtual coordinates on a human neck for 9 human subjects. The achieved accuracy of probe positioning inference is 88%, and the Pearson coefficient (r) of arterial distension estimation is 0.838.

Modular multi-channel high voltage arbitrary waveform generator and imaging setup for dielectric elastomer actuator characterisation

Various applications require multi-channel high-voltage sources for their control, e.g. electrostatic adhesion, electrophoresis and artificial muscles such as piezoelectric, hydraulically amplified self-healing electrostatic(HASEL) and dielectric elastomer actuators(DEAs). Further, the ability to simultaneously monitor the state of the actuators either with images, or voltage and current sensing is crucial to characterise their behaviour. In this work, we present the design of a versatile characterisation setup, capable of generating eight HV (15 kV) arbitrary waveforms(rise time of 8 ms and fall time of 80 ms for 60 MΩ load), while synchronously monitoring voltage and current, and record high-speed (120 fps) video. The setup ensures modularity and customisability by consisting of three independent modules: (1) The imaging module includes a Raspberry Pi and a Pi Camera; (2) A 3.3 V analogue interface 16-bit resolution data acquisition module on a PCB that accommodates a microcontroller board, two 8-channel analogue-to-digital converters, and an 8-channel digital-to-analogue converter; (3) Up to 8 DC-to-HVDC converter boards powered by 12 V DC, with 3.3 V analogue interface.

Integration of Capacitive Pressure Sensor-on-Chip with Lead-Free Perovskite Solar Cells for Continuous Health Monitoring.

The increasing prevalence of hypertension necessitates continuous blood pressure monitoring. This can be safely and painlessly achieved using non-invasive wearable electronic devices. However, the integration of analog, digital, and power electronics into a single system poses significant challenges. Therefore, we demonstrated a comprehensive multi-scale simulation of a sensor-on-chip that was based on a capacitive pressure sensor. Two analog interfacing circuits were proposed for a full-scale operation ranging from 0 V to 5 V, enabling efficient digital data processing. We also demonstrated the integration of lead-free perovskite solar cells as a mechanism for self-powering the sensor. The proposed system exhibits varying sensitivity from 1.4 × 10-3 to 0.095 (kPa)-1, depending on the pressure range of measurement. In the most optimal configuration, the system consumed 50.5 mW, encompassing a 6.487 mm2 area for the perovskite cell and a CMOS layout area of 1.78 × 1.232 mm2. These results underline the potential for such sensor-on-chip designs in future wearable health-monitoring technologies. Overall, this paper contributes to the field of wearable health-monitoring technologies by presenting a novel approach to self-powered blood pressure monitoring through the integration of capacitive pressure sensors, analog interfacing circuits, and lead-free perovskite solar cells.

Design and fabrication of an amperometric CO gas sensor and a readout circuit using a low-noise transimpedance amplifier to achieve standard analog outputs

This article presents a sensor design method that utilizes two electrodes made of gold and tin oxide, along with a gas concentration detection circuit. The use of an n-type semiconductor with a rutile structure contributes to improved sensitivity, and a sol-gel coating with SnO2 is applied. The sensor includes 20 finger electrodes printed on a ceramic substrate, along with a heater placed on the bottom layer to enable interaction with the external environment. The gas concentration is detected through the use of an amperometric method and an ultra-low noise amplifier. The proposed system incorporates a microcontroller and a low-noise analog interface, delivering standard analog outputs ranging from 0 ∼ 10 V and 4 ∼ 20 mA, proportional to the gas concentration. The experimental results demonstrate a sensitivity of 6nA/ppm within the range of 0 ∼ 470 ppm, with a detection limit of 1 ppm. Key advantages of the proposed circuit include linear response within the specified range, resistance to thermal changes, and cost-effectiveness. Moreover, the sensor exhibits reliable repeatability, with a response time of 27.5 s and a recovery time of 39 s. The front-end circuit's adjustable bandwidth and gain enable precise fine-tuning of the measured CO concentration range.

Ring Laser Gyros: Improving Precision and Accuracy Through Soft-Core Processor-Based Active Current Balance Control Approach- Simulation and Implementation Results

In this article, we intend to demonstrate on digital active current control in ring laser gyros (RLG). The specific source errors that effect the performance of laser gyro is discussed. This work proposes a system of digital detection and control system to address deficiencies of the conventional analog circuits. The hardware framework is constructed using the Field Programmable Gate Array (FPGA) and the required analog interface, which incorporates driving and acquisition circuitry for the specific physics of gyros. The software flow is provided in full and uses the parallel PI (proportional-integral) control algorithms. The outcomes demonstrate that the precision of anode currents are accurately controlled within ±0.1µA along with cathode voltage, demonstrating that the performance of the digital system is superior to that of analog circuits, which will be very beneficial for the laser gyro application. The simulation results prove that the proposed approach has good result of balancing anode currents, meanwhile, it makes the sensor a good dynamic performance. In both anodes, the experimental findings are contrasted with balanced and unbalanced currents. The optimal constant current is obtained from the remarkable agreement between simulated and experimental results.

Flight demonstration of a miniature atomic scalar magnetometer based on a microfabricated rubidium vapor cell.

We have developed an atomic magnetometer based on the rubidium isotope 87Rb and a microfabricated silicon/glass vapor cell for the purpose of qualifying the instrument for space flight during a ride-along opportunity on a sounding rocket. The instrument consists of two scalar magnetic field sensors mounted at 45° angle to avoid measurement dead zones, and the electronics consist of a low-voltage power supply, an analog interface, and a digital controller. The instrument was launched into the Earth's northern cusp from Andøya, Norway on December 8, 2018 on the low-flying rocket of the dual-rocket Twin Rockets to Investigate Cusp Electrodynamics 2 mission. The magnetometer was operated without interruption during the science phase of the mission, and the acquired data were compared favorably with those from the science magnetometer and the model of the International Geophysical Reference Field to within an approximate fixed offset of about 550 nT. Residuals with respect to these data sources are plausibly attributed to offsets resulting from rocket contamination fields and electronic phase shifts. These offsets can be readily mitigated and/or calibrated for a future flight experiment so that the demonstration of this absolute-measuring magnetometer was entirely successful from the perspective of increasing the technological readiness for space flight.

Analog interface based on capacitance multiplier for capacitive sensors and application to evaluate the quality of oils

<abstract><p>Currently, interdigital capacitive (IDC) sensors are widely used in science, industry and technology. To measure the changes in capacitance in these sensors, many methods such as differentiation, phase delay between two signals, capacitor charging/discharging, oscillators and switching circuits have been proposed. These techniques often use high frequencies and high complexity to measure small capacitance changes of fF or aF with high sensitivity. An analog interface based on a capacitance multiplier for capacitive sensors is presented. This study includes analysis of the interface error factors, such as the error due to the components of the capacitance multiplier, parasitic capacitances, transient effects and non-ideal parameters of OpAmp. A design approach based on an IDC sensor to measure the quality of edible oils is presented and implemented. The quality relates to the total polar compounds (TPC) and consequently to relative electrical permittivity <inline-formula><tex-math id="M1">\begin{document}$ {\varepsilon }_{r} $\end{document}</tex-math></inline-formula> of the oils. A measurement system has been implemented to measure the capacitance of the IDC sensor, which depended on <inline-formula><tex-math id="M2">\begin{document}$ {\varepsilon }_{r} $\end{document}</tex-math></inline-formula>. The simulation and experimental results showed that, for a capacitance multiplication factor equal to 1000, changes of 3.3 µs/100 fF can be achieved with an acceptable level of noise, which can be easily measured by a microcontroller.</p></abstract>

Accuracy of multiple implant impressions using different combinations of impression materials using closed tray technique: An in vitro study.

Decision for precision! The first stage in creating an accurate, passively fitting prosthesis is to replicate the intraoral relationship of implants using impression methods. The technique and the impression material utilized are the key elements that influence the accuracy of the implant imprint. The goal of this study was to assess the accuracy of the described implant impression technique using various impression materials, as well as to look into the clinical aspects that influence implant impression accuracy. Two holes (4.3 mm × 10 mm) were drilled in a U-shaped study plastic model representing the partially edentulous maxilla, and the appropriate Nobel Biocare Replace select implants were implanted. Closed tray copings were placed for the relevant implants, and closed tray impressions were taken with several impression materials (PVS-1) Dentsply, medium-bodied, and 2) Regular setting-Zhermack Elite HD+). To assess passive fit accuracy, a jig trial and RVG IOPA were used. Stereomicroscopy was used to evaluate the precision of the implant and analog interface from two perspectives: buccal and lingual. On the buccal aspect, Group 1 had a mean value of 13703.29, whereas Group 2 had a mean value of 11395.58. On the lingual aspect, Group 1's mean value was 8415.61, whereas Group 2's was 9192.01. In the closed tray technique, no statistically significant differences between different imprint materials were found. There was no significant difference in the accuracy of closed tray implant impression techniques with different impression materials, according to the findings.

Design of a Flow Meter Interface to be Connected to a Distributed Control System

Flow meters are extremely important in industry. There are many types of flow meters. One of them is one based on Hall effect whose output is modulated square wave which is difficult if not impossible to be caught by most the digital controllers such as DCS, PLC and alike. This paper presents an electronic interface which addresses this problem where it could solve any analog interface almost to any digital controller. The design first signal conditioned the output of the Hall effect sensor, then converts it into voltage which is also signal conditioned to limit the output in the range of 0-5V for 55-550Hz input (1-10L/min). This signal is then converted to 4-20mA current which could easily be read by any digital controller such as PLC, DCS, RTU. Keywords—Flow meter, Hall effect, frequency to voltage converter, voltage current converter

IoT-Based Response Time Analysis of Messages for Smart Autonomous Collision Avoidance System Using Controller Area Network

Many accidents and serious problems occur on the road due to the rapid increase in traffic congestion in all sections of the country. Autonomous vehicles provide a solution to successfully and cost-effectively avoid this problem while minimizing user disruption. Currently, more engaging electromechanical elements with an analog interface are used to develop affordable automobiles for efficient and cost-effective operation for a smart driving platform with a semiautonomous automobile, strengthening the vehicle involvement of the driver while increasing safety. As a result, it takes longer for various car elements to respond, which causes more problems during message transmission. This project aims to create a Controller Area Network (CAN) for analyzing message response times by incorporating a few application nodes on the IoT platform, such as an antilock braking system, flexible cruise control, and seat belt section, for some real-time control system applications. These application nodes are car analytical parts that are linked to IoT modules to prevent collisions. An autonomous device for collision avoidance and obstacle detection in a vehicle can impact road accidents if the CAN protocol is implemented.

Measurement method for capacitive sensors for microcontrollers based on a phase shifter

A complete measurement method dedicated to capacitive sensors has been developed. It includes the development of hardware (an analogue interface circuit for microcontrollers with built-in times/counters and analogue comparators) and software (a measurement procedure and a systematic error calibration (correction) algorithm which is based on a calibration dictionary). The interface circuit consists of a low-pass filter and a phase shifter with a capacitive sensor. A prototype circuit based on a mid-range 8-bit microcontroller has been developed and investigated. We also analysed the relative inaccuracy of a measured capacitance of the sensor and performed experimental research. We obtained the relative errors of capacitance determination < 0.06%, which gives a measurement accuracy < 72 fF for the assumed range of the capacitance (100–300 pF).

Bathing in Lightness

Bathing in Lightness is an interactive audio-visual installation that intends to re- flect our relationship towards the machine as such, regarding the way we tend to perceive the apparatuses around us as living beings with a life of its own. The installation features a swarm intelligence inside a virtual – yet physical – goldfish bowl, that is exploring its tiny universe while trying to communicate with the outer world. The swarm imagines its own interpretation of reality, while reflecting the presence of visitors moving in front of the piece. Build out of a commonly sensed longing for analogue, thus easy understandable mechanisms, the installation’s basic component represents an archetype of electric machines: the incandes- cent light bulb. Thereby the installation acts as an analogue interface through which the visitor can make contact with a virtual being while breaching the digi- tal realm, provoking to contemplate on her/his relationship towards the artificial entity. Along with a calm and soothing sonification of the swarm’s movements, we are allured to rest in front of the piece as we would by warming ourselves at a cozy campfire, remembering us of ancient and more leisurely paced times.

A Conversion Protocol for 2W Telephone Signal over Ethernet in a Private PSTN

In this paper, we proposed a protocol to convert 2W telephone analog signals to Ethernet data in a private PSTN 2W tactical voice system. There are several kinds of operational problems in the tactical telephone network where 2W telephone copper lines are installed hundreds of meters away from the PBX in a headquarter site. The reason is that it is difficult to install and maintain the 2W telephone copper cable in severe operational fields and to meet safety and stability operational requirements of the telephone line under lighting and electromagnetic environments. In order to solve these challenging demands, we proposed an efficient method that the 2W analog interface signals between a private PBX system and a 2W telephone is converted to Ethernet messages using the optical Ethernet data communication network already deployed in the tactical weapon system. Thus, it is not necessary to install an additional optic cable for the ethernet telephone line and to maintain the private PSTN 2W telephone network. Also it provides safe and secure telecommunication operation under lightning and electromagnetic environments.&lt;br/&gt;This paper presents the conversion protocol from 2W telephone signals over Ethernet interface between PBX systems and 2W telephones, the mutual exchange protocol of ethernet messages between two converters, and the rule to process analog signal interface. Finally, we demonstrate that the proposed technique can provide a feasible solution in the tactical weapon system by analyzing its performance and experimental results such as the bandwidth of 2W telephone ethernet network and the transmission latency of voice signal, and the stability of optic ethernet voice network along with the ethernet data network.

Image-Free Ultrasound Blood-Flow Monitoring Circuit System with Automatic Range-Gate Positioning Scheme: A Pilot Study

This work proposes a proof-of-concept ultrasound blood-flow-monitoring circuit system using a single-element transducer. The circuit system consists of a single-element ultrasonic transducer, an analog interface circuit, and a field-programmable gate array (FPGA). Since the system uses a single-element transducer, an ultrasound image cannot be reconstructed unless scanning with mechanical movement is used. An ultrasound blood-flow monitor basically needs to acquire a Doppler sample volume by positioning a range gate at a vessel region on a scanline. Most recent single-transducer-based ultrasound pulsed-wave Doppler devices rely on a manual adjustment of the range gate to acquire Doppler sample volumes. However, the manual adjustment of the range gate depends on the user’s experience, and it can be time consuming if a transducer is not properly positioned. Thus, automatic range-gate-positioning is more desirable for image-free pulsed-wave Doppler devices. This work proposes a circuit system which includes a new automatic range-gate-positioning scheme. It blindly tracks the position of a blood vessel on a scanline by using the accumulation of Doppler amplitude deviations and a hysteresis slicing function. The proposed range-gate-positioning scheme has been implemented in an FPGA for real-time operation and is based on addition-only computations, except for filter parts to reduce the complexity of computation in the hardware. The proposed blood-flow-monitoring circuit system has been implemented with discrete commercial chips for proof-of-concept purposes. It uses a center frequency of 2 MHz and a system-clock frequency of 20 MHz. The FPGA only utilizes 5.6% of slice look-up-tables (LUTs) for implementation of the range-gate-positioning scheme. For measurements, the circuit system was utilized to interrogate a customized flow phantom model, which included two vessel-mimicking channels. The circuit system successfully acquired Doppler sample volumes by positioning a range gate on a fluid channel. In addition, the estimated Doppler shift frequency shows a good agreement with the theoretical value.

Temperature Distribution on Rectangular Composite Plate under Thermal Gradient Loading Environment: Experiment and Simulation

In this paper, the problem is how to calculate the dynamic mechanical and thermal properties. These properties are a function of the temperature at each conditioning load stage. This paper aims to investigate the influence of temperature distribution on a normal deflection through the plate thickness. In the numerical simulation, ANSYS software Ver. 18.2 is used. Both mechanical and thermal properties have been used as inputs in ANSYS software to simulate each point’s temperature distribution on the composite plate. The purpose of this paper is to show that the temperature distribution is crucial in the phases of thermal fatigue (self-heating, thermomechanical degradation, and crack propagation). The composite laminate plate is exposed to out-off plane temperatures in which the temperature gradient is varied between (60 C° and -15 C°). The experiment setup’s potential is the heating and cooling rig environment and the thermocouple connected to an analog interface card. The implication of temperature distribution is in diesel engine design based on durability and reliability. Points (1, 2, 3) have a regular heating and cooling rate (1.574 C/min or -1.574 C/min), while points (4, 5, 6) have an irregular rate of heating and cooling.

Wireless Sensor Networks with Elements of Artificial Intelligence for Medicine

The integrated digitalization of medicine, the use of the AIIoT (Artificial Intelligence IoT), and networks of medical wireless sensors offers new opportunities to remotely support the quality of life of chronically ill patients, the elderly, post-corona pandemic people and athletes and professionals with heavy physical or mental workloads. Wireless sensor networks and computer remote means of maintaining quality of life include smart wearable medical sensors and analog interface. The sensors are intended to monitor heart rate, respiration and blood pressure, determine skin moisture, patient's position and other medical parameters in real time. Miniature interfaces are intended for data acquisition, analog-to-digital conversion, data preprocessing of medical parameters received from wearable medical sensors and data communication to remote diagnostic center. The current state and prospects for the development of these tools are discussed in the publication.

Multimedia Encrypted Experiment of Reconfigurable Wavelength Hopping Protection against Eavesdroppers over a Wireless Wavelength Division Multiplexing Network

To enhance the video transmission security of a physical layer over wireless optical communication, an optical switch configured in front of an arrayed waveguide grating (AWG) router is proposed for implementing reconfigurable wavelength hopping configuration over a wavelength division multiplexing network for protection against eavesdropping. In the practical experiment of an AWG/optical-switch-based random wavelength hopping scheme, a simulated pseudorandom noise generator algorithm was designed and embedded into a master&#x2010;slave microprocessor (e.g., Arduino chips) to generate a time series of electrical signals for triggering an optical switch. The path of the optical switch was randomly varied to change the space transmission of the AWG router. Therefore, varying wavelengths were assigned as the carriers of authorized users to realize the AWG/optical-switch-based wavelength hopping scheme. An optical spectrum analyzer and an oscilloscope were used for monitoring measurement. The experimental results indicated that eavesdroppers cannot accurately interpret analog, digital, audio, and uncompressed high-definition multimedia interface signals of 10&#xA0;MHz, 1&#xA0;MHz, 3.125&#xA0;MHz (encoded into 6.25&#xA0;MHz), and 1.485&#xA0;GHz, respectively. According to the experimental results, authorized and unauthorized users are characterized by a large difference in the retrieved energy signal, which ensures the safety and privacy of the proposed AWG/optical-switch-based reconfigurable wavelength hopping scheme over a wireless optical communication network.

Mode localized artificial hair sensor with enhanced linearity applied for dual-axis air flow sensing

The weakly coupled resonators based on mode localization are promising in emerging signal measurement fields due to the verified relative mechanical sensitivity enhancement and exceptional ambient robustness. In this work, we report a novel mode localized artificial hair sensor for dual-axis air flow sensing. A new full-scale linear output metric based on differential subtraction of reciprocal amplitude ratios (SRAR) is proposed to suppress the strong inherent non-linearity of amplitude ratio-modulated output metric. The theoretical derivation of mechanical sensitivity demonstrates that the differential SRAR output is strictly linear with the square of input air flow velocity. The fabrication process based on standard deep dry silicon on glass is described and an optimized control and measurement system composed of an analog interface circuit and a digital signal processing circuit is designed for experimental performance evaluation. The tested prototype shows an x-axis mechanical sensitivity of 5.417 × 10−2/(m s)−2 with an x-axis cross-axis coupling coefficient of 0.067 and a y-axis sensitivity of 6.212 × 10−2/(m s)−2 with a y-axis cross-axis coupling coefficient of 0.055. The comparative experiment results confirm that compared to frequency-based output and amplitude ratio-based output, the differential SRAR-based output not only promotes the relative mechanical sensitivity and linearity but also exhibits the superior bias stability, which indicates a better common-mode rejection of ambient fluctuations.

Very High Bit Rate Near-Field Communication with Low-Interference Coils and Digital Single-Bit Sampling Transceivers for Biomedical Sensor Systems.

The evolution of microelectronics increased the information acquired by today’s biomedical sensor systems to an extent where the capacity of low-power communication interfaces becomes one of the central bottlenecks. Hence, this paper mathematically analyzes and experimentally verifies novel coil and transceiver topologies for near-field communication interfaces, which simultaneously allow for high data transfer rates, low power consumption, and reduced interference to nearby wireless power transfer interfaces. Data coil design is focused on presenting two particular topologies which provide sufficient coupling between a reader and a wireless sensor system, but do not couple to an energy coil situated on the same substrate, severely reducing interference between wireless data and energy transfer interfaces. A novel transceiver design combines the approaches of a minimalistic analog front-end with a fully digital single-bit sampling demodulator, in which rectangular binary signals are processed by simple digital circuits instead of sinusoidal signals being conditioned by complex analog mixers and subsequent multi-bit analog-to-digital converters. The concepts are implemented using an analog interface in discrete circuit technology and a commercial low-power field-programmable gate array, yielding a transceiver which supports data rates of up to 6.78 MBit/s with an energy consumption of just 646 pJ/bit in transmitting mode and of 364 pJ/bit in receiving mode at a bit error rate of , being 10 times more energy efficient than any commercial NFC interface and fully implementable without any custom CMOS technology.

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