Bio-inspired Sensor Research Articles

Toward Bio-Inspired Tactile Sensing Capsule Endoscopy for Detection of Submucosal Tumors

Here, we present a method for lump characterization using a bio-inspired remote tactile sensing capsule endoscopy system. While current capsule endoscopy utilizes cameras to diagnose lesions on the surface of the gastrointestinal tract lumen, this proposal uses remote palpation to stimulate a bio-inspired tactile sensing surface that deforms under the impression of both hard and soft raised objects. Current capsule endoscopy utilizes cameras to visually diagnose lesions on the surface of the gastrointestinal tract. Our approach introduces remote palpation by deploying a bio-inspired tactile sensor that deforms when pressed against soft or hard lumps. This can enhance visual inspection of lesions and provide more information about the structure of the lesions. Using classifier systems, we have shown that lumps of different sizes, shapes, and hardnesses can be distinguished in a synthetic test environment. This is a promising early start toward achieving a remote palpation system used inside the GI tract that will utilize the clinician’s sense of touch.

A Research on Effect of Probed Object Shape on Frequency Inflection Point (FIP) of Underwater Active Electrolocation System

Weakly electric fish can orient and navigate in dark environment by their active electrolocation system. Bio-inspired active electrolocation sensor has been investigated. In previous work, amplitude information-frequency characteristics (AIFC) of the active electrolocation system have been investigated. Detect frequency dead zone and frequency inflection point (FIP) of AIFC for the electrolocation system were found. And FIP have relevance to the material properties and geometric features of the probed object and the conductivity of surrounding water. But how to the shape of the probed object influence on FIP has not been deeply researched. In order to deeply study on how to the probed object shape influence on FIP of the active electrolocation system, three different materials probed object with two different shapes with similar geometric features of the probed object were selected for the active electrolocation system experiment. The following conclusions were obtained: for the similar size and the same material of the probed object, the shape of the probed object has significant effect on FIP of AIFC for the electrolocation system. So the shape of the probed object may affect the electric image. It may have a reference value for active electrolocation system designing.

Bio-inspired directional sensor with piezoelectric microfiber and helical electrodes

Inspired by the hair cells of vertebrates and aquatics, we proposed a hair sensor design that mimics the directionality and linearity of hair cells. The sensor promotes a novel use of piezoelectric microfiber with unique helical electrodes. The sensing mechanism was modeled both analytically and numerically. The analytical model explicitly illustrates the effects of the various design parameters on the performance of the sensor; the numerical model took into account the complex geometry of the sensor and elucidated the importance of the orientation of piezoelectric polarization on the piezoelectric effects. Both models provide valuable insight to optimize the sensor performance. Hair sensor prototypes were fabricated and characterized in the laboratory. The sensor output was found to be linearly dependent on the magnitude of applied displacements. Besides, at the same magnitude of deflection, the sensor responses followed a cosine function with the loading direction, which is similar to what is observed on the directionality of biological hair cells. These experimental observations were consistent with the results of model simulations. An algorithm was proposed to determine the magnitude and direction of acoustic stimuli by utilizing just a pair of orthogonally polarized and closely spaced hair cell sensors.

A study of active artificial hair cell models inspired by outer hair cell somatic motility

The cochlea displays an important, nonlinear amplification of sound-induced oscillations. In mammals, this amplification is largely powered by the somatic motility of the outer hair cells. The resulting cochlear amplifier has three important characteristics useful for hearing: an amplification of responses from low sound pressures, an improvement in frequency selectivity, and an ability to transduce a broad range of sound pressure levels. These useful features can be incorporated into designs for active artificial hair cells, bio-inspired sensors for use as microphones, accelerometers, or other dynamic sensors. The sensor consists of a cantilever beam with piezoelectric actuators. A feedback controller applies a voltage to the actuators to mimic the outer hair cells’ somatic motility. This article describes three control laws for an active artificial hair cell inspired by models of the outer hair cells’ somatic motility. The first control law is based on a phenomenological model of the cochlea while the second and third models incorporate physiological aspects of the biological cochlea to further improve sensor performance. Simulations show that these models qualitatively reproduce the key aspects of the mammalian cochlea, namely, amplification of oscillations from weak stimuli, higher quality factors, and a wider input dynamic range.

Micromechanical properties of strain-sensitive lyriform organs of a wandering spider (Cupiennius salei)

Highly sensitive lyriform organs located on the legs of the wandering spider Cupiennius salei allow the spider to detect nanometer-scale strains in the exoskeleton resulting from locomotion or substrate vibrations. Morphological features of the lyriform organs result in their specialization and selective sensitivity to specific mechanical stimuli, which make them interesting for bioinspired strain sensors. Here we utilize atomic force microscopy (AFM)-based force spectroscopy to probe nano-scale mechanical properties of the covering membrane of two lyriform organs found on Cupiennius salei: the vibration sensitive metatarsal lyriform organ (HS10) and the proprioreceptive tibial lyriform organ (HS8). Force distance curves (FDCs) obtained from AFM measurements displayed characteristic multi-layer structure behavior, with calculated elastic moduli ranging from 150MPa to 500MPa for different regions and indentation depths. In addition, we probed the lyriform organs with a large radius tip, which allowed for probing structural deformation by the application of high forces and large scale deformations without damaging the surface. The viscoelastic behavior of the sensor materials observed in this probing suggests mechanical relaxation times potentially playing a role in the time-dependent behavior of the lyriform organs. Statement of SignificanceHighly sensitive lyriform organs located on the legs of the wandering spider Cupiennius salei allow the spider to detect nanometer-scale strains in the exoskeleton resulting from locomotion or substrate vibrations. Morphological features of the lyriform organs result in their specialization and selective sensitivity to specific mechanical stimuli, which make them an interesting for bioinspired strain sensors. Here we utilize atomic force microscopy (AFM)-based force spectroscopy to probe nano-scale mechanical properties of the covering membrane of two lyriform organs found on Cupiennius salei: the vibration sensitive metatarsal lyriform organ (HS10) and the proprioreceptive tibial lyriform organ (HS8). Force distance curves (FDCs) obtained from AFM measurements displayed characteristic multi-layer structure behavior, with calculated elastic moduli ranging from 150MPa to 500MPa for different regions and indentation depths. The viscoelastic behavior of the sensor materials observed in this probing suggests mechanical relaxation times playing a role in the time-dependent behavior of the lyriform organs.

Calibration of a polarization navigation sensor using the NSGA-II algorithm

A bio-inspired polarization navigation sensor is designed based on the polarization sensitivity mechanisms of insects. A new calibration model by formulating the calibration problem as a multi-objective optimization problem is presented. Unlike existing calibration models, the proposed model makes the calibration problem well-posed. The calibration parameters are optimized through Non-dominated Sorting Genetic Algorithm-II (NSGA-II) approach to minimize both angle of polarization (AOP) residuals and degree of linear polarization (DOLP) dispersions. The results of simulation and experiments show that the proposed algorithm is more stable than the compared methods for the calibration applications of polarization navigation sensors.

Design and Calibration of a Novel Camera-Based Bio-Inspired Polarization Navigation Sensor

The remarkable ability of animals using the skylight polarization pattern provides a significant inspiration for the autonomous robotic navigation. The bio-inspired polarization navigation approach with advantages of efficiency and reliability has aroused much interesting for experts to perform further research. The sensor of measuring the skylight polarization pattern plays a key role in bio-inspired polarization navigation. A novel camera-based bionic polarization navigation sensor is designed and implemented. We propose a robust measurement method based on the least squares by utilizing all outputs of measurement units. For improving the precision of measurement, the errors of sensor are analyzed, and an effective calibration algorithm is proposed in detail. The experiment results show that the measurement accuracy is improved greatly after calibration. Finally, to evaluate the performance of our sensor, experiments of measuring the actual skylight polarization pattern are performed and compared with the results from the single-scattering Rayleigh theory. The comparison results indicate that our sensor can achieve an effective and accuracy measurement in practice.

Miniaturized chemical sensor with bio-inspired micropillar working electrode array for lead detection

A disposable, miniaturized and compact microelectromechanical systems (MEMS) chemical sensor incorporated with three-dimensional, free-standing micropillar working electrode array was proposed, fabricated and tested for electrochemical detection of lead ions. Inspiration of designing arch-shaped columnar sensing electrode array originated from the biological imitation of shark’s olfactory sensing system, considering shark has developed ultrasensitive olfactory capacity during the evolutionary processes. The analytical performance of proposed bio-inspired MEMS chemical sensor was comprehensively investigated. Under optimal conditions, high sensitivity of 32nA/(μg/L) as well as favorable detection limit of 0.2μg/L was achieved with short deposition time of 30s. The sensor exhibited linear responses to lead ions in the concentration range from 1 to 130μg/L with good linearity (correlation coefficient: 0.9994). The collection efficiency towards target ions in the preconcentration step was significantly enhanced by the presence of micropillar electrode array, due to both the enlargement of electrode surface area and the interaction effect between protruding micropillars and moving solution. Proposed MEMS chemical sensor eliminates the involvement of mechanical/forced stirring of testing solution, making it a potential alternative to conventional macro-sized electrochemical sensor for the application of on-site determination of heavy metal contamination.

Bio-Inspired Stretchable Absolute Pressure Sensor Network.

A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles.

A Bio-Inspired Vision Sensor With Dual Operation and Readout Modes

This paper presents a novel event-based vision sensor with two operation modes: 1) intensity mode and spatial contrast detection. They can be combined with two different readout approaches: 1) pulse density modulation and time-to-first spike. The sensor is conceived to be a node of an smart camera network made up of several independent an autonomous nodes that send information to a central one. The user can toggle the operation and the readout modes with two control bits. The sensor has low latency (below 1 ms under average illumination conditions), low power consumption (19 mA), and reduced data flow, when detecting spatial contrast. A new approach to compute the spatial contrast based on inter-pixel event communication less prone to mismatch effects than diffusive networks is proposed. The sensor was fabricated in the standard AMS4M2P 0.35- $\mu \text{m}$ process. A detailed system-level description and experimental results are provided.

Bio-inspired sensors based on photonic structures of Morpho butterfly wings: a review

This review summarizes the state-of-the-art development of Morpho butterfly wings used for various physical and chemical sensors.

Analytical development of a binuclear oxo-manganese complex bio-inspired on oxidase enzyme for doping control analysis of acetazolamide

A bio-inspired electrochemical sensor using a binuclear oxo-manganese complex was evaluated and applied in the detection of a substance associated with doping in sports: acetazolamide (ACTZ). Investigation was made of the influence of different experimental variables on the electrocatalytic oxidation of ACTZ by the bio-inspired sensor, such as pH and interfering species. The bio-inspired sensor showed the best response in the range from 5.00×10−9 to 7.00×10−8molL−1 ACTZ, with a linear range from 5.00×10−9 to 2.50×10−8molL−1 and a detection limit of 4.76×10−9molL−1. The sensor exhibited characteristics similar to the Michaelis–Menten model of an enzymatic electrode, due to the use of a multinucleated complex of manganese with μ-oxo units, which was able to mimic the properties of enzymes with manganese as a cofactor in their composition, such as Mn-containing oxidase. The determination of ACTZ with the bio-inspired sensor was evaluated using three different synthetic biological fluids (plasma, saliva, and urine), demonstrating its viability for use with real samples. The analysis of ACTZ in real urine samples using the bio-inspired sensor, simulating the method adopted by the World Anti-Doping Agency, which revealed viable, suggesting a new and promising platform to be used in these analysis.

Maximum-Likelihood Estimator of Clock Offset between Nanomachines in Bionanosensor Networks.

Recent advances in nanotechnology, electronic technology and biology have enabled the development of bio-inspired nanoscale sensors. The cooperation among the bionanosensors in a network is envisioned to perform complex tasks. Clock synchronization is essential to establish diffusion-based distributed cooperation in the bionanosensor networks. This paper proposes a maximum-likelihood estimator of the clock offset for the clock synchronization among molecular bionanosensors. The unique properties of diffusion-based molecular communication are described. Based on the inverse Gaussian distribution of the molecular propagation delay, a two-way message exchange mechanism for clock synchronization is proposed. The maximum-likelihood estimator of the clock offset is derived. The convergence and the bias of the estimator are analyzed. The simulation results show that the proposed estimator is effective for the offset compensation required for clock synchronization. This work paves the way for the cooperation of nanomachines in diffusion-based bionanosensor networks.

Biologically inspired time-delay soft sensors for online monitoring of automotive coldstart operations: a comparative analysis

In this paper, an attempt is made to develop a bio-inspired soft sensor as a real-time identifier for online estimations of the engine-out hydrocarbon emission and exhaust gas temperature over the coldstart operation of an automotive engine. To date, a number of studies have been done to design soft models as offline identifiers for capturing the knowledge of a set of collected coldstart databases. The results indicated that bio-inspired computation can be of great use for the identification of coldstart phenomenon. It also can be a good alternative to classic approaches. However, bio-inspired soft sensors have not been used as online estimators for monitoring the behavior of coldstart phenomenon. This is while it is desirable to have a flexible, inexpensive online identifier which can be employed to detect the real-time behavior of the engine over coldstart periods. Here, an exhaustive numerical study is conducted to demonstrate the potentials of bio-inspired approaches for online measuring of engine-out hydrocarbon emission and exhaust gas temperature during the coldstart operation. To do so, a set of well-known bio-inspired optimizers are combined with a time-delayed artificial neural network to design an evolvable soft sensor. The results clearly demonstrate the high potential of bio-inspired computation for handling the difficulties associated with the real-time identification of engine-out hydrocarbon emission and exhaust gas temperature.

Bio-inspired piezoelectric artificial hair cell sensor fabricated by powder injection molding

A piezoelectric artificial hair cell sensor was fabricated by the powder injection molding process in order to make an acoustic vector hydrophone. The entire process of powder injection molding was developed and optimized for PMN–PZT ceramic powder. The artificial hair cell sensor, which consists of high aspect ratio hair cell and three rectangular mechanoreceptors, was precisely fabricated through the developed powder injection molding process. The density and the dielectric property of the fabricated sensor shows 98% of the theoretical density and 85% of reference dielectric property of PMN–PZT ceramic powder. With regard to homogeneity, three rectangular mechanoreceptors have the same dimensions, with 3 μm of tolerance with 8% of deviation of dielectric property. Packaged vector hydrophones measure the underwater acoustic signals from 500 to 800 Hz with −212 dB of sensitivity. Directivity of vector hydrophone was acquired at 600 Hz as analyzing phase differences of electric signals.

A study of amplitude information-frequency characteristics for underwater active electrolocation system

Weakly electric fish sense their surroundings in complete darkness by their active electrolocation system. For biologists, the active electrolocation system has been investigated for near 60 years. And for engineers, bio-inspired active electrolocation sensor has been investigated for about 20 years. But how the amplitude information response will be affected by frequencies of detecting electric fields in the active electrolocation system was rarely investigated. In this paper, an electrolocation experiment system has been built. The amplitude information-frequency characteristics (AIFC) of the electrolocation system for sinusoidal electric fields of varying frequencies have been investigated. We find that AIFC of the electrolocation system have relevance to the material properties and geometric features of the probed object and conductivity of surrounding water. Detect frequency dead zone (DFDZ) and frequency inflection point (FIP) of AIFC for the electrolocation system were found. The analysis model of the electrolocation system has been investigated for many years, but DFDZ and FIP of AIFC can be difficult to explain by those models. In order to explain those AIFC phenomena for the electrolocation system, a simple relaxation model based on Cole–Cole model which is not only a mathematical explanation but it is a physical one for the electrolocation system was advanced. We also advance a hypothesis for physical mechanism of weakly electrical fish electrolocation system. It may have reference value for physical mechanism of weakly electrical fish active electrolocation system.

A Bio-Inspired AER Temporal Tri-Color Differentiator Pixel Array.

This article investigates the potential of a bio-inspired vision sensor with pixels that detect transients between three primary colors. The in-pixel color processing is inspired by the retinal color opponency that are found in mammalian retinas. Color transitions in a pixel are represented by voltage spikes, which are akin to a neuron's action potential. These spikes are conveyed off-chip by the Address Event Representation (AER) protocol. To achieve sensitivity to three different color spectra within the visual spectrum, each pixel has three stacked photodiodes at different depths in the silicon substrate. The sensor has been fabricated in the standard TSMC 90 nm CMOS technology. A post-processing method to decode events into color transitions has been proposed and implemented as a custom interface to display real-time color changes in the visual scene. Experimental results are provided. Color transitions can be detected at high speed (up to 2.7 kHz). The sensor has a dynamic range of 58 dB and a power consumption of 22.5 mW. This type of sensor can be of use in industrial, robotics, automotive and other applications where essential information is contained in transient emissions shifts within the visual spectrum.

Suboptimal lunar landing GNC using nongimbaled optic-flow sensors

Autonomous planetary landing is a critical phase in every exploratory space mission. Autopilots have to be safe, reliable, energy saving, and as light as possible. The 2-D guidance, navigation, and control strategy presented here makes use of biologically inspired landing processes. Based solely on the relative visual motion known as optic flow (OF), assessed with minimalistic 6-pixel 1-D OF sensors and inertial measurement unit measurements, an optimal reference trajectory in terms of the mass was defined for the approach phase. Linear and nonlinear control laws were then implemented to track the optimal trajectory. To deal with the demanding weight constraints, a new method of OF estimation was applied, based on a nongimbaled OF sensor configuration and a linear least-squares algorithm. The promising results obtained with software-in-the-loop simulations showed that the present full guidance, navigation, and control solution combined with our OF bio-inspired sensors is compatible with soft, fuel-efficient lunar spacecraft landing and might also be used as a backup solution in case of conventional-sensor failure.

Hostile fire detection using a bio-inspired mobile acoustic sensor network

Hostile Fire Detection (HFD) sensors play an increasing role in combating asymmetric threats in both military and civilian operations. Bio-inspired advances in acoustic sensor technology have enabled small aperture arrays to localize and identify target sounds on baselines as small as 7.5 cm, making them practical for body worn and mobile applications such as UAVs. The unique approach to acoustic processing reduces acoustic information through a neural transform to key features that allow segregation of multiple targets using spectro-temporal cues creating auditory objects. The sparse representation of targets as auditory objects enables fast computationally efficient localization, identification, and tracking of several acoustic targets nearly simultaneously. The sparse representation is also ideal for information fusion among sensors over limited bandwidth networks for enhanced performance in challenging environments. Through a collaborative effort between Army research groups, the University of California Santa Barbara, and BioMimetic Systems, a prototype acoustic sensor network using biologically inspired sensors and network synchronization for a mobile HFD application has been developed. The network employs body worn PinPoint™ HFD sensors interfaced with smartphones (Android) running net-centric fusion algorithms. The network will be discussed in terms of the biologically inspired components, information fusion, as well as results from preliminary field tests.

Scoping biology-inspired chemical engineering

Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineering (BioChE) may be recognized as a significant branch of chemical engineering. It may consist of, but not limited to, the following three aspects: 1) Chemical engineering principles and unit operations in biological systems; 2) Process engineering principles for producing existing or developing new chemical products through living ‘devices’; and 3) Chemical engineering processes and equipment that are designed and constructed through mimicking (does not have to reproduce one hundred percent) the biological systems including their physical–chemical and mechanical structures to deliver uniquely beneficial performances. This may also include the bio-inspired sensors for process monitoring. In this paper, the above aspects are defined and discussed which establishes the scope of BioChE.