Biomimetic Sensor Research Articles

Application of Molecularly Imprinted Electrochemical Biomimetic Sensors for Detecting Small Molecule Food Contaminants.

Environmental chemical contaminants in food seriously impact human health and food safety. Successful detection methods can effectively monitor the potential risk of emerging chemical contaminants. Among them, molecularly imprinted polymers (MIPs) based on electrochemical biomimetic sensors overcome many drawbacks of conventional detection methods and offer opportunities to detect contaminants with simple equipment in an efficient, sensitive, and low-cost manner. We searched eligible papers through the Web of Science (2000-2022) and PubMed databases. Then, we introduced the sensing mechanism of MIPs, outlined the sample preparation methods, and summarized the MIP characterization and performance. The classification of electrochemistry, as well as its advantages and disadvantages, are also discussed. Furthermore, the representative application of MIP-based electrochemical biomimetic sensors for detecting small molecular chemical contaminants, such as antibiotics, pesticides, toxins, food additives, illegal additions, organic pollutants, and heavy metal ions in food, is demonstrated. Finally, the conclusions and future perspectives are summarized and discussed.

Biomimetic Perception, Cognition, and Control: From Nature to Robots [From the Guest Editors

A wide range of technological developments are inspired by biological individuals and advanced synthetic materials, cognitive sensors, control algorithms, artificial intelligence technology, and intelligent systems. One of the major challenges is to create a comprehensive study by integrating different techniques into robotic systems so that the performance of robots can be improved and applied to more complex and diverse scenarios. The articles in this issue focus on the state of the art in biomimetic perception, cognition, and control research and aim to explore related technical avenues in the multimodal bioinformation perception framework, intelligent cognition and learning, robotic systems and control, and new biomimetic sensors.

Engineered olfactory system for in vitro artificial nose

• Artificial nose drew generous attention in the field of bionic organs • Construction with sensing module, recognition system and functional structure are introduced • Recognition technology, substrate materials and microarray integration in artificial nose are prospected The engineered biomimetic sensors can not only realize the action of organs, but also combine functional materials as in vitro organs by simulating the response of biological organs to different environmental signals. Artificial nose is a concept proposed by imitating biological olfactory system, simulating olfactory nerve cells, olfactory bulb and olfactory cortex through different materials to realize olfactory function. The sensor array used to sense external gas stimulation can be analyzed based on different recognition principles through different original signals such as optics, electricity, electrochemistry and bioelectricity. Furthermore, combined with pattern recognition and microarray technology, artificial nose can be highly integrated with biocompatible and other important properties to achieve in vitro application. The design principle and necessary components of artificial nose are introduced in this paper including sensing structure, recognition system and functional module. At the same time, the potential development prospects of molecular recognition technology, polymer-based materials and microarray integration in artificial nose are prospected.

Design of a biomimetic cellulose nanofibre-based double information encryption sensor for fingerprint imaging

The development of double encryption system enables information to switch reversibly between “False” and “True”, which helps to ensure information security in the transmission process. Herein, a biomimetic cellulose nanofibre-based double information encryption sensor (CNF-DIES) with an excellent pH response and fluorescence colour-switching performance was prepared with fluorescein isothiocyanate and protoporphyrin IX modified acetylated cellulose nanofibres (ACNF) as the pH response switch and background, respectively. Interestingly, with the addition of cellulose, CNF-DIES can be regarded as both a dye and an ink binder, which can realize direct writing function. The fluorescein grafted to ACNF guaranteed the stability of writing and avoided the “coffee ring” phenomenon. The handwriting written by CNF-DIES processes excellent light/pH double encryption performance. Besides, the film prepared by CNF-DIES can realize high resolution fingerprint imaging. This work demonstrated a strategy for pH-responsive colour-tunable materials for sensors and double information encryption.

Biomimetic functional material-based sensors for food safety analysis: A review

Food may be contaminated by various hazardous substances in all stages of the food supply chain, which may pose a wide variety of human health risks. The ability to construct sensors capable of highly selective analysis in complex food matrix could offer strong support for guaranteeing food safety. The design, preparation, and introduction of biomimetic functional materials as antifouling materials or recognition receptors provide new ideas for further improvement of the anti-interference and specificity of sensory system. Herein, biomimetic functional materials commonly used in sensor preparation, including biomimetic antifouling materials [poly(ethylene glycol), zwitterionic polymers, and synthetic antifouling peptides] and biomimetic recognition receptors (molecularly imprinted polymers, aptamers, and mimetic recognition peptides) are reviewed. The mechanisms, advantages, limitations of these biomimetic functional materials and the applications of biomimetic functional material-based sensors in food safety analysis are summarized. Finally, the challenges and prospects of sensors based on biomimetic functional materials are analyzed.

A ratiometric electrochemical sensing platform based on multifunctional molecularly imprinted polymer with catalytic activity for the detection of psychoactive substances

Molecularly imprinted polymers (MIPs) are widely used as artificial recognition element in sensing field, but their electrochemical sensing performances are generally affected by their poor catalytic activity and unruly condition change. In this work, an MIP film with catalysis (Fe-DMMIP) is constructed by electrodeposition of Fe-coordinated aminophenanthroline and 3,4-ethylenedioxythiophene on N, S doped C material, using cannabinoid (CBD) as template molecule. Due to the presence of Fe–N active sites, the obtained Fe-DMMIP possesses enzyme-like catalytic activity besides conventional recognition capability. Accordingly, the sensor exhibits high electrocatalytic activity and selectivity. Moreover, the Fe-DMMIP can produce a stable and well-defined signal as an internal reference around 0 V (vs. Ag/AgCl) for ratiometric sensing. Under the optimal conditions, the ratiometric signal is linear to CBD concentration in the range of 0.004–0.8 μmol L−1 (R2 = 0.9946) with a detection limit of 2.9 nmol L−1. The ratiometric sensor shows high reproducibility, stability and applicability. In addition, through replacing the template molecule, the resulting biomimetic sensor also exhibits good performance in sensing other psychoactive substances such as melatonin and 5-hydroxytryptophan, with LODs of 19 nmol L−1 and 8 nmol L−1for them, respectively. Therefore, the developed sensing platform has good prospects, and this work provides a new way for developing ratiometric electrochemical sensors with high sensitivity, reproducibility and anti-interference ability.

Assessment of the Microbial Spoilage and Quality of Marinated Chicken Souvlaki through Spectroscopic and Biomimetic Sensors and Data Fusion.

Fourier-transform infrared spectroscopy (FT-IR), multispectral imaging (MSI), and an electronic nose (E-nose) were implemented individually and in combination in an attempt to investigate and, hence, identify the complexity of the phenomenon of spoilage in poultry. For this purpose, marinated chicken souvlaki samples were subjected to storage experiments (isothermal conditions: 0, 5, and 10 °C; dynamic temperature conditions: 12 h at 0 °C, 8 h at 5 °C, and 4 h at 10 °C) under aerobic conditions. At pre-determined intervals, samples were microbiologically analyzed for the enumeration of total viable counts (TVCs) and Pseudomonas spp., while, in parallel, FT-IR, MSI, and E-nose measurements were acquired. Quantitative models of partial least squares-Regression (PLS-R) and support vector machine-regression (SVM-R) (separately for each sensor and in combination) were developed and validated for the estimation of TVCs in marinated chicken souvlaki. Furthermore, classification models of linear discriminant analysis (LDA), linear support vector machine (LSVM), and cubic support vector machines (CSVM) that classified samples into two quality classes (non-spoiled or spoiled) were optimized and evaluated. The model performance was assessed with data obtained by six different analysts and three different batches of marinated souvlaki. Concerning the estimation of the TVCs via the PLS-R model, the most efficient prediction was obtained with spectral data from MSI (root mean squared error-RMSE: 0.998 log CFU/g), as well as with combined data from FT-IR/MSI (RMSE: 0.983 log CFU/g). From the developed SVM-R models, the predictions derived from MSI and FT-IR/MSI data accurately estimated the TVCs with RMSE values of 0.973 and 0.999 log CFU/g, respectively. For the two-class models, the combined data from the FT-IR/MSI instruments analyzed with the CSVM algorithm provided an overall accuracy of 87.5%, followed by the MSI spectral data analyzed with LSVM, with an overall accuracy of 80%. The abovementioned findings highlighted the efficacy of these non-invasive rapid methods when used individually and in combination for the assessment of spoilage in marinated chicken products regardless of the impact of the analyst, season, or batch.

Single-use biomimetic sensors for rapid and sensitive cortisol detection in blood

The detection of biomarkers in blood using portable point-of-care (POC) devices can provide immense benefits for disease diagnosis and healthcare management. Electrochemical biosensors with rapid response, accuracy, high sensitivity, miniaturization, and portability are particularly advantageous for such applications. Here, we report on a photolithographically micropatterned, biomimetic organic 3-electrode impedimetric sensor (O3ES) for the ultralow volume (single drop – 10 μL) detection of cortisol in whole blood. The O3ES comprising a soft conducting polymer (PEDOT:PSS) and silk protein matrix provides a stable electrochemical signal from whole blood with minimal biofouling interference. A water-based, ambient processing of the sensors allows the immobilization of antibodies in the working electrode which act as the specific biorecognition molecules for cortisol. The increase in charge transfer resistance due to cortisol-antibody binding at the electrode surface is monitored to obtain a calibration curve via electrochemical impedance spectroscopy. The O3ES displays a linear and specific sensitivity towards cortisol in whole blood in the range of 0.01–50 μg dL−1. The flexible O3ES strips are designed to be discarded after a single use. This work demonstrates the realization of low-cost, disposable, organic POC sensors capable of detecting steroid hormones using ultralow sample volumes.

A Novel Synthesis of a Magnetic Porous Imprinted Polymer by Polyol Method Coupled with Electrochemical Biomimetic Sensor for the Detection of Folate in Food Samples

The present study reports the development and application of a novel, sensitive, and selective voltammetric sensor for the quantitation of folate or vitamin B9 in foodstuffs. The sensor was made from magnetic molecularly imprinted polymers (MMIPs), which were synthesized by the core–shell method using magnetite nanoparticles obtained by the polyol method. The MMIP-based sensor was used for the selective and specific detection of folate in different food samples. The MMIP material was constructed using magnetic water-dispersible nanomaterial, which was prepared by immersing iron (III) acetylacetonate in tri-ethylene-glycol (TEG) solvent. The magnetic water-dispersible nanomaterial was then subjected to polymerization using allyl alcohol as a functional monomer, ethylene-glycol-dimethacrylate (EGDMA) as a cross-linking agent, and 2,2-Azobisisobutyronitrile (AIBN) as a radical initiator. The proposed magnetic materials were characterized by Brunauer–Emmett–Teller (BET), field emission gun scanning electron microscopy (FEG-SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analysis. The quantification of folate was performed by square wave voltammetry under optimized conditions using 15 mg of MMIPs and 85 mg of carbon paste. The modified electrode presented a linear dynamic range (LDR) of 2.0–12 µmol L−1 and a limit of detection (LOD) of 1.0 × 10−7 mol L−1 in 0.1 mol L−1 acetate buffer solution (pH 4.0). The proposed sensor was successfully applied for folate detection in different food samples, where recovery percentages ranging from 93 to 103% were obtained. Finally, the results obtained from the analysis of selectivity showed that the modified biomimetic sensor is highly efficient for folate determination in real food samples. Adsorption tests were used to evaluate and compare the efficiency of the MMIPs and magnetic non-molecularly imprinted polymer (MNIPs)—used as control material, through the application of HPLC as a standard method.

Interface electronic engineering of molybdenum sulfide/MXene hybrids for highly efficient biomimetic sensors

Interface electronic engineering of molybdenum sulfide/MXene hybrids for highly efficient biomimetic sensors

DigiTac: A DIGIT-TacTip Hybrid Tactile Sensor for Comparing Low-Cost High-Resolution Robot Touch

Deep learning combined with high-resolution tactile sensing could lead to highly capable dexterous robots. However, progress is slow because of the specialist equipment and expertise. The DIGIT tactile sensor offers low-cost entry to high-resolution touch using GelSight-type sensors. Here we customize the DIGIT to have a 3D-printed sensing surface based on the TacTip family of soft biomimetic optical tactile sensors. The DIGIT-TacTip (DigiTac) enables direct comparison between these distinct tactile sensor types. For this comparison, we introduce a tactile robot system comprising a desktop arm, mounts and 3D-printed test objects. We use tactile servo control with a PoseNet deep learning model to compare the DIGIT, DigiTac and TacTip for edge- and surface-following over 3D-shapes. All three sensors performed similarly at pose prediction, but their constructions led to differing performances at servo control, offering guidance for researchers selecting or innovating tactile sensors. All hardware and software for reproducing this study will be openly released. Project website: www.lepora.com/digitac. Project repository: www.github.com/nlepora/digitac-design.

Antenna-Shaped Biomimetic Tactile Sensor Using Elastomers and Conductive Liquid

The antenna of an insect has inspired researchers to develop various types of antenna-mimicking tactile sensors. We suggest a conductive liquid-based biomimetic tactile covered with elastomers, focusing on imitating its anatomical features. The polyethylene glycol (PEG) and silver nitrate composite proved its compatibility with elastomers and its reliability as a conductive material. The working mechanism of the sensor established from the conductive liquid and wires was investigated. A three-dimensional (3D) printer-driven fabrication process facilitated the applicability of the sensor to an integrated biomimetic robot for military purposes. Wall scanning tests using multiple sensors and walls with various geographical features showed a linear relationship between bending angles and resistance with outstanding coefficients of determination up to 0.9889. Especially, wall scanning experiments at a fixed distance led to their geographical reconstruction with high accuracy. Our antenna-shaped tactile sensor was made with alternative elements, a simple fabrication process, and an alternative working mechanism. It also demonstrated high repeatability on the basis of bending angles and showed the possibility to be used for 3D image reconstruction.

A table-top sensor for the detection of hydrophobins and yeasts in brewery applications

In this work, we present a biomimetic sensor for the sensitive and fast (< 15 min) detection of yeast cells (S. cerevisiae) and hydrophobins (e.g. HFB) in food and beverages. While unwanted yeast contaminations can cause off-flavors and stability issues, hydrophobin contaminations are a less-known but equally serious economic concern in beer production. Hydrophobins are small proteins, that are produced by pathogenic fungi that often infect barley. Due to their high temperature stability, HFBs survive all stages of brewing and, after bottling, they cause excessive foaming due to interactions between the HFBs, CO2, and glass surfaces. Tiny HFB concentrations are sufficient to cause this “gushing” and up to 10% of beer production is therefore discarded. Hence, an early-stage HFB detection, preferably even before malting, would reduce the loss of resources. However, existing tests are time-consuming and have sub-optimal accuracy. The novel sensor platform has a user-friendly design that combines impedimetric readout with wire-type electrodes, coated with poly-pyrrole layers that are imprinted with Trichoderma reesei hydrophobin I (HFBI) molecules or with yeast cells. In complex food samples, the sensor reaches detection limits of 50 yeast cells/mL (in yoghurt solution) and below 30 ng/mL HFBI in top-fermented beer samples. Cross-selectivity tests with proteins of similar size show a response to Hyd5 (another hydrophobin) and discrimination against insulin. As a final proof of application, we demonstrate hydrophobin detection directly in extracts of industrial malt samples with and without a natural hydrophobin contamination.

Noninvasive, wireless and real-time bladder pressure monitoring with biomimetic structured devices

Urinary bladder pressure (UBP) is a crucial physiological parameter reflecting urinary incontinence, abdominal pressure and abdominal visceral injury. Realizing the real−time monitoring UBP change helps the development of diagnosing either chronic or severe abdominal diseases. However, current clinic facilities or invasive devices are expensive, complicated to manipulate, low sensitivity, and excruciating to patients. Herein, we propose a noninvasive UBP wireless measurement system using a biomimetic structured piezoresistive sensor and low−power Bluetooth. Our piezoresistive pressure sensor can fully reach a sensitivity of 0.19 kPa−1 in the range of 0−3 kPa and exhibits significant robustness after 1000 cycles. The low−power Bluetooth system could transmit data in real−time to realize an intelligent diagnosis. Our integration system provides an efficient strategy to help clinicians or patients diagnose abdominal impairment in real-time.

Flexible assembled tactile sensor with freely integration design

Flexible touch-sensing devices have become increasingly multifunctional in wearable interaction electronics owing to the diversification of material synthesis and the flexibility in the structure design. Especially, the latter provides capabilities for the existing sensors owning the common materials with new possibilities to acquire certain requisite functions. Herein, we designed a strain sensor by assembling the nature rubber (NR) substrate with the MoS2/MWCNT conducting network structure. For demonstrating the flexibility of the proposed integrated model under the application of NR, practical applications were exhibited. The bendable biomimetic hair sensor is integrated into the smart car for robotic tactile to imitate the manner of mammals when sensing the surroundings. Besides, a flexible sensing array can be designed into arbitrary shapes according to users’ requirements manifesting its flexibility and practicability. What is more, the sensor used as electronic skin (e-skin) can realize tactile sensing and meanwhile monitor human body movements. The success of this study paves the way for extending this technology to tactile sensing which is a promising lead to develop multifunctional strain sensors for widespread applications.

Multicolor fluorescent supramolecular adhesive gels based on a single molecule with aggregation-induced ratiometric emission

Multicolor fluorescent materials, showing various fluorescent colors at the same time, have been applied in biomimetic materials, sensor arrays, and information storage. However, the vast majority of present multicolor fluorescent materials were prepared within a complicated as well as costly process, which was achieved by incorporating a variety of fluorophores. Herein, we designed multicolor fluorescent supramolecular adhesive gels (MSAGs) based on single pyrene benzohydrazonate (PBHZ) fluorophore. When the concentration of PBHZ groups was adjusted, the gel blocks that make up MSAGs exhibited distinct fluorescence colors ranging from blue to bright green due to the aggregation-induced ratiometric emission (AIRE) effect. In addition, as a consequence of 2-ureido-4-pyrimidone (UPy) units containing in the gel blocks, MSAGs could be facilely obtained through interfacial supramolecular adhesion between these gel blocks. Moreover, the resulting MSAGs with various patterns showed superiority in applying to encrypt multiple information.

High Sensitivity and Wide Range Biomimetic Tactile-Pressure Sensor Based on 2D Graphene Film and 3D Graphene Foam.

Bionic electronic skin is a system that simulates human skin and has multiple perceptions. For pressure sensors, high measurement accuracy and wide measurement range restrict each other, and it is difficult to achieve high measurement accuracy and wide measurement range simultaneously. Therefore, the research and application of bionic tactile-pressure sensors are limited due to the mutual constraints of measurement accuracy and range. In this work, a flexible graphene piezoresistive tactile sensor based on a biomimetic structure that utilizes the piezoresistive properties of graphene was reported. The novel tactile-pressure sensor consists of a 2D graphene film tactile sensor and a 3D graphene foam pressure sensor that could achieve high accuracy and a wide-range measurement simultaneously. The testing results show that the measurement range of this sensor was in two intervals of 0–2 N and 2–40 N. For the 0–2 N measurement range, the sensitivity was 472.2 Ω/kPa, the force resolution was 0.01 N, and the response time was less than 40 ms. For the 2–40 N measurement range, the sensitivity was 5.05 kΩ/kPa, the force resolution was 1 N, and the response time was less than 20 ms. The new sensor can realize high-precision and large-scale force measurements and shows great application value in the field of medical instruments and artificial limbs.

GTac: A Biomimetic Tactile Sensor With Skin-Like Heterogeneous Force Feedback for Robots

The tactile sensing capabilities of human hands are essential in daily activities. Simultaneously perceiving normal and shear forces via the mechanoreceptors integrated into the hands allow us humans to achieve daily tasks like grasping delicate objects. In this paper, we design and fabricate a biomimetic tactile sensor with skin-like heterogeneity that perceives normal and shear contact forces simultaneously. It mimics the multilayered structure of mechanoreceptors in human skin by combining an extrinsic layer (piezoresistive sensors) and an intrinsic layer (a Hall sensor) so that it can perform estimation of contact force directions, locations, and joint-level torque. By integrating our sensors, a robotic gripper can obtain contact force feedback at the fingertips; accordingly, robots can perform challenging tasks, such as using tweezers and grasping eggs. This insightful sensor design can be customized and applied in different areas of robotics and provide them with heterogeneous force sensing, potentially supporting robotics in acquiring skin-like tactile feedback.

Mapping Mid-Air Haptics With a Low-Cost Tactile Robot

Mid-air haptics create a new mode of feedback to allow people to feel tactile sensations in the air. Ultrasonic arrays focus acoustic radiation pressure in space, to induce tactile sensation from the resulting skin deflection. In this work, we present a low-cost tactile robot to test mid-air haptics. By combining a desktop robot arm with a 3D-printed biomimetic tactile sensor, we developed a system that can sense, map, and visualize mid-air haptic sensations created by an ultrasonic transducer array. We evaluate our tactile robot by testing it on a variety of mid-air haptic stimuli, including unmodulated and modulated focal points that create a range of haptic shapes. We compare the mapping of the stimuli to another method used to test mid-air haptics: Laser Doppler Vibrometry, highlighting the advantages of the tactile robot including far lower cost, a small lightweight form-factor, and ease-of-use. Overall, these findings indicate our method has multiple benefits for sensing mid-air haptics and opens up new possibilities for expanding the testing to better emulate human haptic perception.

Single-Atom Iron Anchored on 2-D Graphene Carbon to Realize Bridge-Adsorption of O-O as Biomimetic Enzyme for Remarkably Sensitive Electrochemical Detection of H2O2.

Single-atom catalysis is mainly focused on its dispersed high-density catalytic sites, but delicate designs to realize a unique catalysis mechanism in terms of target reactions have been much less investigated. Herein an iron single atomic site catalyst anchored on 2-D N-doping graphene (Fe-SASC/G) was synthesized and further employed as a biomimetic sensor to electrochemically detect hydrogen peroxide, showing an extremely high sensitivity of 3214.28 μA mM-1 cm-2, which is much higher than that (6.5 μA mM-1 cm-2) of its dispersed on 1-D carbon nanowires (Fe-SASC/NW), ranking the best sensitivity among all reported Fe based catalyst at present. The sensor was also used to successfully in situ monitor H2O2 released from A549 living cells. The mechanism was further systematically investigated. Results interestingly indicate that the distance between adjacent single Fe atomic catalytic sites on 2-D graphene of Fe-SASC/G matches statistically well with the outer length of bioxygen of H2O2 to promote a bridge adsorption of -O-O- for simultaneous 2-electron transfer, while the single Fe atoms anchored on distant 1-D nanowires in Fe-SASC/NW only allow an end-adsorption of oxygen atoms for 1-electron transfer. These results demonstrate that Fe-SASC/G holds great promise as an advanced electrode material in selective and sensitive biomimetic sensor and other electrocatalytic applications, while offering scientific insights in deeper single atomic catalysis mechanisms, especially the effects of substrate dimensions on the mechanism.