Self-calibration Capabilities Research Articles

Enhancing the electrical readout of the spin-dependent recombination current in SiC JFETs for EDMR based magnetometry using a tandem (de-)modulation technique

Electrically detected magnetic resonance (EDMR) is a promising method to readout spins in miniaturized devices utilized as quantum magnetometers. However, the sensitivity has remained challenging. In this study, we present a tandem (de-)modulation technique based on a combination of magnetic field and radio frequency modulation. By enabling higher demodulation frequencies to avoid 1/f-noise, enhancing self-calibration capabilities, and eliminating background signals by 3 orders of magnitude, this technique represents a significant advancement in the field of EDMR-based sensors. This novel approach paves the way for EDMR being the ideal candidate for ultra-sensitive magnetometry at ambient conditions without any optical components, which brings it one step closer to a chip-based quantum sensor for future applications.

Self-calibrated NICE-OHMS based on an asymmetric signal: theoretical analysis and experimental validation.

As an ultra-sensitive detection technique, the noise-immune cavity enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) technique has great potential for assessment of the concentration of trace gases. To determine gas concentrations at the ppt or lower level with high accuracy, it is desirable that the technique exhibits self-calibration (or calibration-free) capabilities. Although being sensitive, NICE-OHMS has so far not demonstrated any such ability. To remedy this, this paper provides a self-calibrated realization of NICE-OHMS that is based on a switching of the feedback target of the DeVoe-Brewer (DVB) locking procedure from the modulation frequency of the frequency modulation spectroscopy (FMS) to the cavity length, which creates an asymmetrical signal whose form and size can be used to unambiguously assess the gas concentration. A comprehensive theoretical model for self-calibrated NICE-OHMS is established by analyzing the shift of cavity modes caused by intracavity absorption, demonstrating that gas absorption information can be encoded in both the laser frequency and the NICE-OHMS signal. To experimentally verify the methodology, we measure a series of dispersion signals under different levels of absorbance using a built experimental setup. An instrument factor and the partial pressure are obtained by fitting the measured signal through theoretical expressions. Our results demonstrate that fitted values are more accurate for higher partial pressures than for lower. To improve on the accuracy at low partial pressures, it is shown that the instrument factor obtained by fitting the signal at large partial pressures (in this case, above 7.8 µTorr) can be set to a fixed value for all fits. By this, the partial pressures can be assessed with a relative error below 0.65%. This technique has the potential to enable calibration-free ultra-sensitive gas detection.

Competitive Ratiometric Aptasensing with Core-Internal Standard-Shell Structure Based on Surface-Enhanced Raman Scattering

Reproducibility and stability are important indicators for the evaluation of quantitative sensing methods based on surface-enhanced Raman scattering (SERS) technology. Developing a SERS substrate with self-calibration capabilities is vital for effectively quantifying targets. In this work, a competitive ratiometric SERS aptasensor was developed. 4-Aminothiophenol as an internal standard (IS) was embedded in the substrate followed by gradually loading with the aptamer and methylene blue functionalizing of the complementary sequences of the aptamer (MB-cDNA). Recognition and binding of the target to the aptamer resulted in the shedding of MB-cDNA after magnetic separation reducing the SERS signal of MB, allowing for the ratiometric determination of the target based on the constant intensity from the IS. For the selective detection of okadaic acid (OA), a good negative correlation was achieved between the SERS ratiometric intensity and OA concentration in the range of 0.5-100 ng/mL. The magnetic separation strategy effectively simplifies the production steps of the aptasensor, and the ratiometric strategy effectively improved the reproducibility and stability of the OA sensing. This ratiometric aptasensor has been successfully employed to detect OA in food and environmental samples and is expected to be extended to detect other targets.

Development of a Flexible Integrated Self-Calibrating MEMS Pressure Sensor Using a Liquid-to-Vapor Phase Change.

Self-calibration capabilities for flexible pressure sensors are greatly needed for fluid dynamic analysis, structure health monitoring and wearable sensing applications to compensate, in situ and in real time, for sensor drifts, nonlinearity effects, and hysteresis. Currently, very few self-calibrating pressure sensors can be found in the literature, let alone in flexible formats. This paper presents a flexible self-calibrating pressure sensor fabricated from a silicon-on-insulator wafer and bonded on a polyimide substrate. The sensor chip is made of four piezoresistors arranged in a Wheatstone bridge configuration on a pressure-sensitive membrane, integrated with a gold thin film-based reference cavity heater, and two thermistors. With a liquid-to-vapor thermopneumatic actuation system, the sensor can create precise in-cavity pressure for self-calibration. Compared with the previous work related to the single-phase air-only counterpart, testing of this two-phase sensor demonstrated that adding the water liquid-to-vapor phase change can improve the effective range of self-calibration from 3 psi to 9.5 psi without increasing the power consumption of the cavity micro-heater. The calibration time can be further improved to a few seconds with a pulsed heating power.

Numerical Study of the Thermal Performance of a Mems Pressure Sensor with Self-Calibration Capabilities.

Recent industry trends toward more complex and interconnected systems have increased the demand for more reliable pressure sensors. By integrating a microactuator with a pressure sensor, the sensor can self-calibrate, eliminating the complexities and costs associated with traditional sensor calibration methods to ensure reliability. The present work is focused on furthering understanding and improving the thermal performance of a thermopneumatic actuated self-calibrating pressure sensor. A transient numerical model was developed in ANSYS and was calibrated using experimental testing data. The numerical model provided insights into the sensor’s performance not previously observed in experimental testing. Furthermore, the model was utilized for two design studies. First, it was found that a substrate with low thermal conductivity and high thermal diffusivity is ideal for both the sensor’s efficiency and a faster transient response time. The second design study showed that decreasing the size of the sealed reference cavity lowers power consumption and transient response time. The study also showed that reducing the cavity base dimension has a greater effect on lowering power consumption and response time. Overall, the present work increases understanding of the self-calibrating pressure sensor and provides insight into potential design improvements, moving closer to optimized self-calibrating pressure sensors.

Design and implementation of smart pressure sensor for automotive applications

No doubt that the measurement is an important matter in the precise and accurate control of automotive subsystems to improve the performance and efficiency. The key tool to achieve high degree of precision and accuracy in control applications is sensor. In recent years, the rapid technological advances have revolutionized the automotive industry and a great variety of new sensors are introduced to the market with the purpose of accelerating the development of autonomous vehicles technology. However, the increasing legal pressures from regulatory authorities have led to strengthened requirements for robust pressure sensors in vehicles. On the other hand, the cost of such devices need to remain low due to the continual competition in the market. In this study, we have proposed a low cost piezoresistive sensing method based smart pressure sensor, which combines the signal conditioning, analog/digital signal processing and communication circuitry directly to the sense element in a single compact housing. The introduced smart pressure sensor achieves the improved reliability and greater accuracy due to its built-in temperature compensation, filtering and self-calibration capabilities. The measurement performance of our prototype design has been tested in dynamic test device, which can control the working status of a typical vehicle compressor. The experimental results validate the robustness of the proposed smart pressure sensor in terms of linearity, repeatability and data transmission.

Modelling of heat stress in a robotic dairy farm. Part 2: Identifying the specific thresholds with production factors

Thresholds of heat stress are identified by determining the values of thermal comfort indices with significant change of animal responses. However, published thresholds may lead to inaccuracy when dealing with specific climate conditions, animal breeds and production factors. Thus, determining dynamic thresholds might provide better assessment of heat stress, with self-calibration capabilities. In this study, a large dataset of individual age, body mass (BM), days in milk (DIM), daily milk yield (DMY) and milk temperature (MT) of 126 lactating Holstein cows was collected from a robotic dairy farm over five years. The ambient temperature data was collected from a local weather station and processed as daily minimum and mean temperature (Tmin and Tmean). For the whole herd, a new series of heat stress thresholds with stages were defined as comfort stage, milk heat stress, effective heat stress and critical heat stress. The definition was based on the cow's responses in DMY and MT, which provides a potential approach to accurately alert for heat stress in robotic farming systems by using the existing data source. For the specific individuals, dynamic thresholds of heat stress were identified and categorised using the decision tree machine learning model. The categorisation achieved 79–94% overall accuracy, and demonstrated the importance of cooling cows during their early lactation period.

Simultaneous quantification of multiple biomarkers on a self-calibrating microfluidic paper-based analytic device

In this study, we developed a point-of-care assay platform with simultaneous detection and self-calibration capabilities for multiple targets based on a microfluidic paper-based analytical device (μPAD). This system is easily manufactured using a wax printing method on chromatographic paper. The design pattern consists of a zone of detection and a calibrant zone for controlled loading using wax barriers with different thicknesses. We showed the utility and applicability of this approach by a proof-of-concept study for two clinically important markers: glucose and lactate. With the naked eye, the results could be fully distinguished and recorded to evaluate the analytical performance with a flatbed scanner. The detection limits of glucose and lactate were 0.3125 mM and 0.2975 mM, respectively, and simultaneous detection was possible from a small sample (0.4 μL) with high sensitivity. Furthermore, this device has a self-calibration function, which minimizes the influence of environmental conditions (i.e., ambient light intensity, temperature, humidity, and pressure). Therefore, the developed multiplex paper-based device is promising for clinical multianalyte point-of-care testing since it is easy to manufacture, cost-effective, user-friendly, and highly sensitive.

On the self-calibration capabilities of gamma -ray energy tracking arrays

.Gamma-ray energy tracking arrays constitute the technological frontier of high-resolution gamma -ray spectroscopy revolutionizing modern nuclear physics investigations. Their principle of operation lies on the precise reconstruction of the three-dimensional gamma -ray interaction positions within the detector volume. The most common method to obtain these interaction points in real time is to compare the experimental signals against a reliable library of signals (signal basis) that maps the detector response as a function of the gamma -ray interaction position. Obtaining a high-fidelity signal basis, however, remains a big technological challenge, which hinders the optimal operation of these state-of-the-art arrays. In this article, we propose a pioneering and notably simple method for generating experimentally a reliable signal basis. The proposed method enables the gamma -ray tracking devices to perform a self-calibration of their position sensitive response in situ, opening up the way for reaching their optimum performance for the first time.

Correction of axial position uncertainty and systematic detector errors in ptychographic diffraction imaging

Ptychography is a diffraction imaging method that allows one to solve inverse problems in microscopy with the ability to retrieve information about and correct for systematic errors. Here, we propose techniques to correct for axial position uncertainty, detector point spread, and inhomogeneous detector response using ptychography’s inherent self-calibration capabilities. The proposed methods are tested with visible light and x-ray experimental data. We believe that the results are important for precise calibration of ptychographic experimental setups and rigorous quantification of partially coherent beams by means of ptychography.

A Low-Cost Open-Source Acoustic Recorder for Bioacoustics Research.

Acoustic recorders are the primary tool used in marine bioacoustics; however, available devices are either expensive or lack self-calibration capabilities that are critical for high-quality measurements. Moreover, the software used in proprietary designs can be inflexible and may involve unknown processing steps. To address this, we have designed a miniature low-cost yet high-performance acoustic recorder that features open-source hardware and software. Circuitry is included for self-calibration, making it possible to evaluate device performance in situ. Our intention is that the design will develop in conjunction with the needs of the bioacoustics community.

Micro-grating tilt sensor with self-calibration and direct intensity modulation

A micro-grating tilt sensor based on phase diffraction grating with self-calibration capability and direct intensity modulation is proposed. The optical tilt sensor consists of a coherent light source, gold gratings patterned on the transparent substrate, a silicon proof mass supported by the eight symmetrical Al cantilevers. Al membrane is sputtered on the bottom of the proof mass. Both Au and Al membrane serve as electrodes for electrostatic actuation. This can provide the sensitivity adjustment and self-calibration capabilities. Experiments show that the inclinometer provides the maximum incline sensitivity of 90mV/°, resolution of 0.00006°, a measurement range of±5° in the rotational plane that is parallel to the direction of the gravity, and good self-calibration ability with electrostatic actuation.

Micrograting Displacement Sensor with Integrated Electrostatic Actuation

A high-resolution micro-grating displacement sensor with diffraction-based and integrated electrostatic actuation is proposed and experimentally demonstrated. The Al reflecting membrane is fabricated at the bottom of a silicon moving part and the Au micro-gratings are patterned on a transparent substrate. This structure forms a phase sensitive diffraction grating, providing the displacement sensitivity of the micro-grating interferometer. It shows sensitivity adjustment and self-calibration capabilities with electrostatic actuation. Additional system components include a coherent light source, photodiodes, and required electronics. Experimental results show that the displacement sensor has a sensitivity of about 1.8 mV/nm and a resolution of less than 1 nm in the linear region. This displacement sensor is very promising in the fields requiring high sensitivity, broad dynamic range, and immunity to electromagnetic interference.

70.1: Touch‐Interactive High Power Efficiency AMOLED Display with Energy Recycling and Self‐Calibration Capabilities

AbstractA polarizer‐less OLED is introduced with 30% improvement in efficiency. Also, the new OLED structure provides integrated multi‐touch, power recycling/generating, and non‐uniformity /aging self‐calibration capabilities.

NIMS-PL: A Cable-Driven Robot With Self-Calibration Capabilities

We present the Networked InfoMechanical System for Planar Translation, which is a novel two-degree-of-freedom (2-DOF) cable-driven robot with self-calibration and online drift-correction capabilities. This system is intended for actuated sensing applications in aquatic environments. The actuation redundancy resulting from in-plane translation driven by four cables results in an infinite set of tension distributions, thus requiring real-time computation of optimal tension distributions. To this end, we have implemented a highly efficient, iterative linear programming solver, which requires a very small number of iterations to converge to the optimal value. In addition, two novel self-calibration methods have been developed that leverage the robot's actuation redundancy. The first uses an incremental displacement, or jitter method, whereas the second uses variations in cable tensions to determine end-effector location. We also propose a novel least-squares drift-detection algorithm, which enables the robot to detect long-term drift. Combined with self-calibration capabilities, this drift-monitoring algorithm enables long-term autonomous operation. To verify the performance of our algorithms, we have performed extensive experiments in simulation and on a real system.

Improved self-calibrated spiral parallel imaging using JSENSE

Spiral MRI has several advantages over Cartesian MRI such as faster acquisitions and reduced demand in gradient. In parallel imaging, spiral trajectories are especially of great interest due to their inherent self-calibration capabilities, which is especially useful for dynamic imaging applications such as fMRI and cardiac imaging. The existing self-calibration techniques use the central spiral data that are sampled densely in the accelerated acquisition for coil sensitivity estimation. However, the resulting sensitivities are not sufficiently accurate for SENSE reconstruction due to the data truncation. In this paper, JSENSE which has been successfully used in Cartesian trajectories is extended to spiral trajectory such that the coil sensitivities and the desired image are reconstructed jointly to improve accuracy through alternating optimization. The improved sensitivities lead to a more accurate SENSE reconstruction. The results from both phantom and in vivo data are shown to demonstrate the effectiveness of JSENSE for spiral trajectory.

Mars navigation system utilizes GPS

Tasks envisioned for future generation Mars rovers - sample collection, area survey, resource mining, habitat construction, etc. - will require greatly enhanced navigational capabilities over those possessed by the Mars Sojourner rover. Many of these tasks will involve cooperative efforts by multiple rovers and other agents, adding further requirements both for accuracy and commonality between users. This paper presents a new navigation system a Self-Calibrating Pseudolite Array (SCPA) that can provide centimeter-level, drift-free localization to multiple rovers within a local area by utilizing GPS-based transceivers deployed in a ground-based array. Such a system of localized beacons can replace or augment a system based on orbiting satellite transmitters, and is capable of fully autonomous operations and calibration. This paper describes the prototype SCPA developed at Stanford to demonstrate these capabilities and then presents results from a set of field trials performed at NASA Ames Research Center. These experiments, which utilize the K9 Mars rover research platform, validate both the navigation and self-calibration capabilities of the system. By carrying an on-board GPS transceiver, K9 was successfully able to calibrate the system using no a priori position information and localized the pseudolite beacons to under 5 cm RMS.

Integrated microanalytical system with electrochemical detection

A complete microanalytical system for ionometric measurements in liquids with self-testing and self-calibration capabilities has been developed. Several advanced microtechniques are used leading to a modular setup consisting of two basic units: (i) a sensor/actuator unit and (ii) a controller unit for signal handling, actuator control and system management. As sensors ion sensitive field effect transistors (ISFET) are mounted in a plexiglass microflow cell; their alternate contact with sample and calibration solution is achieved with micropumps. These pumps are also made of polymeric materials. A special aspect of the system is the transport of liquid by means of gas pumping (air). The stacked arrangement of all components results in small overall dimensions of the system. The principal system functions have been demonstrated, and short measurement cycles were observed.