Mobile recognition and positioning for multiple visible light communication cells using a convolutional neural network: publisher's note.

This publisher's note contains a correction to Opt. Lett.48, 6468 (2024)10.1364/OL.503007.

Natural Polysaccharide Film-Based Triboelectric Sensor for Fruit Transportation Collision Monitoring.

Transportation-induced damage to fresh produce is a big challenge in logistics. Current acceleration and pressure sensors for collision monitoring face issues of power dependency, high cost, and environmental concerns. Here, a self-powered and environmentally friendly triboelectric sensor has been developed to monitor fruit collisions in transportation packaging. Microcrystalline cellulose/chitosan and sodium alginate films were prepared as positive and negative tribo-layers to assemble a natural polysaccharide film-based triboelectric nanogenerator (NP-TENG). The NP-TENG's electrical output was proportional to the structure parameters (contact surface roughness and separation gap of the tribo-layers) and the vibration factors (force and frequency) and exhibited excellent stability and durability (over 100,000 cycles under 13 N at 10 Hz). The high mechanical-to-electrical conversion efficiency (instantaneous areal power density of 9.6 mW/m2) and force sensitivity (2.2 V/N) enabled the NP-TENG to be a potential sensor for monitoring fresh produce collisions in packaging during logistics. Transportation simulation measurements of kiwifruits verified that the sensor's electrical outputs increased with the vibration frequency and stacking layer while varying at different packaging locations. This study suggests that the NP-TENG can effectively monitor collision damage during fruit transportation, providing new insights into developing intelligent food packaging systems to reduce postharvest supply chain losses.

Borneol serves as an adjuvant agent to promote the cellular uptake of curcumin for enhancing its photodynamic fungicidal efficacy against Candida albicans.

Candida albicans (C. albicans), a major opportunistic pathogenic fungus, is known to cause superficial skin infections. Unfortunately, the misuse of antibiotics has led to the emergence of drug resistance in fungi. Antimicrobial photodynamic therapy (aPDT), a non-antibiotic alternative, has shown potential in treating drug-resistant fungal infections. Curcumin is a photodynamically active phytochemical whose photodynamic fungicidal efficacy is largely dependent on its intracellular accumulation. However, curcumin faces challenges in penetrating the cytoplasm due to its poor water solubility and the fungal cell wall. Borneol, another monoterpenoid phytochemical, is known for its ability to enhance drug absorption. In this study, we showed that borneol improved the cellular uptake of curcumin, thereby enhancing its photodynamic fungicidal efficacy against C. albicans. This effect was attributed to borneol's ability to increase cell permeability. Transcriptomic analysis further confirmed that borneol disrupted the normal structure and function of the C. albicans cell wall and membrane, resulting in dysregulated mRNA expression of related genes and ultimately increased cell permeability. As a result, the excessive accumulation of curcumin in C. albicans triggered the overproduction of intracellular ROS upon exposure to blue light. These excessive intracellular ROS disrupted various cellular structures, interfered with essential cellular processes, inhibited biofilm formation and reduced virulence. Remarkably, borneol was also found to enhance curcumin uptake by C. albicans within biofilms, further enhancing the anti-biofilm efficacy of curcumin-mediated aPDT (Cur-aPDT). In conclusion, the results of this study strongly support the potential of borneol as an adjuvant agent to Cur-aPDT in treating superficial cutaneous fungal infections.

Injectable, self-healing hyaluronic acid-based hydrogels for spinal cord injury repair.

The cystic cavity that develops following spinal cord injury is a major obstacle for repairing spinal cord injury (SCI). The injectable self-healing biomaterials treatment is a promising strategy to enhance tissue repair after traumatic spinal cord injury. Herein, a natural extracellular matrix (ECM) biopolymer hyaluronic acid-based hydrogel was developed based on multiple dynamic covalent bonds. The hydrogels exhibited excellent injectable and self-healing properties, could be effectively injected into the injury site, and filled the lesion cavity to accelerate the tissue repair of traumatic SCI. Moreover, the hydrogels were compatible with cells and various tissues and possessed proper stiffness matched with nervous tissue. Additionally, when implanted into the injured spinal cord site, the hyaluronic acid-based hydrogel promoted axonal regeneration and functional recovery by accelerating remyelination, axon regeneration, and angiogenesis. Overall, the injectable self-healing hyaluronic acid-based hydrogels are ideal biomaterials for treating traumatic SCI.

Mobile recognition and positioning for multiple visible light communication cells using a convolutional neural network.

The industrial Internet of Things (IIoT) environment involves multiple production items, such as robots and automated guided vehicles (AGVs), among others. The practical industrial scenario requires communication of production items while also considering mobile recognition and positioning. Hence the perception approach requires not only combining communications but also realizing the recognition and positioning of multiple communication cells. This Letter proposes a multi-optical cell recognition and positioning framework based on LED image features. The LED images are obtained by a CMOS image sensor. This framework utilizes convolutional neural networks (CNN) to train LED images for recognition between multiple optical cells and locates precise positions through region recognition within the optical cells. The experimental results show that the mean accuracy of the CNN model for two LED cells is above 99%, and the mean accuracy of region recognition within the optical cell is as high as 100%, which is significantly better than other traditional recognition algorithms. Therefore, the proposed framework can provide location-aware services for visible light communication and has a wide application prospect in IIoT.

Recent advances and research progress on microsystems and bioeffects of terahertz neuromodulation.

Terahertz waves can interact with the nervous system of organisms under certain conditions. Compared to common optical modulation methods, terahertz waves have the advantages of low photon energy and low risk; therefore, the use of terahertz waves to regulate the nervous system is a promising new method of neuromodulation. However, most of the research has focused on the use of terahertz technology for biodetection, while relatively little research has been carried out on the biological effects of terahertz radiation on the nervous system, and there are almost no review papers on this topic. In the present article, we begin by reviewing principles and objects of research regarding the biological effects of terahertz radiation and summarizing the current state of related research from a variety of aspects, including the bioeffects of terahertz radiation on neurons in vivo and in vitro, novel regulation and detection methods with terahertz radiation devices and neural microelectrode arrays, and theoretical simulations of neural information encoding and decoding. In addition, we discuss the main problems and their possible causes and give some recommendations on possible future breakthroughs. This paper will provide insight and assistance to researchers in the fields of neuroscience, terahertz technology and biomedicine.

RIS-aided dynamically adaptive wide field-of-view receiver for visible light communication in industrial internet of things.

In the current visible light communication (VLC) system, a condenser lens is generally used in the front of receiver to achieve a higher data rate, making an extremely narrow field-of-view for the receiver. With the spread of Industrial Internet of Things (IIoT), the communication between mobile terminals is urgently required. A wide-range detecting method for VLC system in IIoT scenario is asked. In this paper, a novel self-adaptive wide-FoV receiver involving reconfigurable intelligent surfaces (RIS) is proposed. The effective detecting range of the receiver can be expanded by dynamically adjusting the incident light directions with the assistance of RIS. Based on the maximum arrived flux criterion, the mathematical model is established and the optimized RIS parameter tuning algorithm is presented. The feasibility and validity of the method are verified by simulation. The results show that the tolerable transceiver offset can be increased to 2∼4 times as the conventional receiver.

Impaired Spatial Firing Representations of Neurons in the Medial Entorhinal Cortex of the Epileptic Rat Using Microelectrode Arrays.

Epilepsy severely impairs the cognitive behavior of patients. It remains unclear whether epilepsy-induced cognitive impairment is associated with neuronal activities in the medial entorhinal cortex (MEC), a region known for its involvement in spatial cognition. To explore this neural mechanism, we recorded the spikes and local field potentials from MEC neurons in lithium-pilocarpine-induced epileptic rats using self-designed microelectrode arrays. Through the open field test, we identified spatial cells exhibiting spatially selective firing properties and assessed their spatial representations in relation to the progression of epilepsy. Meanwhile, we analyzed theta oscillations and theta modulation in both excitatory and inhibitory neurons. Furthermore, we used a novel object recognition test to evaluate changes in spatial cognitive ability of epileptic rats. After the epilepsy modeling, the spatial tuning of various types of spatial cells had suffered a rapid and pronounced damage during the latent period (1 to 5 d). Subsequently, the firing characteristics and theta oscillations were impaired. In the chronic period (>10 d), the performance in the novel object experiment deteriorated. In conclusion, our study demonstrates the detrimental effect on spatial representations and electrophysiological properties of MEC neurons in the epileptic latency, suggesting the potential use of these changes as a "functional biomarker" for predicting cognitive impairment caused by epilepsy.

Highly Activated Neuronal Firings Monitored by Implantable Microelectrode Array in the Paraventricular Thalamus of Insomnia Rats.

Insomnia is a common sleep disorder around the world, which is harmful to people's health, daily life, and work. The paraventricular thalamus (PVT) plays an essential role in the sleep-wake transition. However, high temporal-spatial resolution microdevice technology is lacking for accurate detection and regulation of deep brain nuclei. The means for analyzing sleep-wake mechanisms and treating sleep disorders are limited. To detect the relationship between the PVT and insomnia, we designed and fabricated a special microelectrode array (MEA) to record electrophysiological signals of the PVT for insomnia and control rats. Platinum nanoparticles (PtNPs) were modified onto an MEA, which caused the impedance to decrease and improved the signal-to-noise ratio. We established the model of insomnia in rats and analyzed and compared the neural signals in detail before and after insomnia. In insomnia, the spike firing rate was increased from 5.48 ± 0.28 spike/s to 7.39 ± 0.65 spike/s, and the power of local field potential (LFP) decreased in the delta frequency band and increased in the beta frequency band. Furthermore, the synchronicity between PVT neurons declined, and burst-like firing was observed. Our study found neurons of the PVT were more activated in the insomnia state than in the control state. It also provided an effective MEA to detect the deep brain signals at the cellular level, which conformed with macroscopical LFP and insomnia symptoms. These results laid the foundation for studying PVT and the sleep-wake mechanism and were also helpful for treating sleep disorders.

Detection of neuronal defensive discharge information transmission and characteristics in periaqueductal gray double-subregions using PtNP/PEDOT:PSS modified microelectrode arrays.

Threatened animals respond with appropriate defensive behaviors to survive. It has been accepted that midbrain periaqueductal gray (PAG) plays an essential role in the circuitry system and organizes defensive behavioral responses. However, the role and correlation of different PAG subregions in the expression of different defensive behaviors remain largely unexplored. Here, we designed and manufactured a microelectrode array (MEA) to simultaneously detect the activities of dPAG and vPAG neurons in freely behaving rats. To improve the detection performance of the MEAs, PtNP/PEDOT:PSS nanocomposites were modified onto the MEAs. Subsequently, the predator odor was used to induce the rat's innate fear, and the changes and information transmission in neuronal activities were detected in the dPAG and vPAG. Our results showed that the dPAG and vPAG participated in innate fear, but the activation degree was distinct in different defense behaviors. During flight, neuronal responses were stronger and earlier in the dPAG than the vPAG, while vPAG neurons responded more strongly during freezing. By applying high-performance MEA, it was revealed that neural information spread from the activated dPAG to the weakly activated vPAG. Our research also revealed that dPAG and vPAG neurons exhibited different defensive discharge characteristics, and dPAG neurons participated in the regulation of defense responses with burst-firing patterns. The slow activation and continuous firing of vPAG neurons cooresponded with the regulation of long-term freezing responses. The results demonstrated the important role of PAG neuronal activities in controlling different aspects of defensive behaviors and provided novel insights for investigating defense from the electrophysiological perspective.

PtNPs/PEDOT:PSS-Modified Microelectrode Arrays for Detection of the Discharge of Head Direction Cells in the Retrosplenial Cortex of Rats under Dissociation between Visual and Vestibular Inputs.

The electrophysiological activities of head direction (HD) cells under visual and vestibular input dissociation are important to understanding the formation of the sense of direction in animals. In this paper, we fabricated a PtNPs/PEDOT:PSS-modified MEA to detect changes in the discharge of HD cells under dissociated sensory conditions. The electrode shape was customized for the retrosplenial cortex (RSC) and was conducive to the sequential detection of neurons at different depths in vivo when combined with a microdriver. The recording sites of the electrode were modified with PtNPs/PEDOT:PSS to form a three-dimensional convex structure, leading to closer contact with neurons and improving the detection performance and signal-to-noise ratio of the MEA. We designed a rotating cylindrical arena to separate the visual and vestibular information of the rats and detected the changes in the directional tuning of the HD cells in the RSC. The results showed that after visual and vestibular sensory dissociation, HD cells used visual information to establish newly discharged directions which differed from the original direction. However, with the longer time required to process inconsistent sensory information, the function of the HD system gradually degraded. After recovery, the HD cells reverted to their newly established direction rather than the original direction. The research based on our MEAs revealed how HD cells process dissociated sensory information and contributes to the study of the spatial cognitive navigation mechanism.

Flexible dual-functionalized hyaluronic acid hydrogel adhesives formed in situ for rapid hemostasis.

Hydrogel adhesives integrating both rapid and strong adhesion to blooding tissues and biocompatibility are highly desired for fast hemostasis. Herein, a flexible hyaluronic acid hydrogel adhesive is fabricated via photocrosslinking of the solution originating from dopamine-conjugated maleic hyaluronic acid (DMHA) in situ. The introduction of acrylate groups with high substitutions into the hydrogel matrix endows the adhesive with rapid gelation and strong tissue adhesion properties through photopolymerization. Moreover, the high substitution of catechol groups with unoxidized state can not only induce red blood cell aggregation and platelets adhesion but also adhere to wound tissue to further enhance hemostasis. Based on its bio-adhesion and procoagulant activity, the DMHA hydrogel formed in situ reveals superior hemostatic performance in the rat liver injury model and noncompressible hemorrhage model, and rabbit femoral artery puncture model, compared to commercial products (gauze, absorbable gelatin sponge) and oxidized DMHA (SMHA) hydrogel. Besides, the hydrogel exhibited good adaptability, biodegradability, and superior cytocompatibility as well as negligible inflammation. This hydrogel adhesive is a promising biological adhesive for hemorrhage control.

PtNPs/rGO-GluOx/mPD Directionally Electroplated Dual-Mode Microelectrode Arrays for Detecting the Synergistic Relationship between the Cortex and Hippocampus of Epileptic Rats.

Precise and directional couplings of functional nanomaterials with implantable microelectrode arrays (IMEAs) are critical for the manufacture of sensitive enzyme-based electrochemical neural sensors. However, there is a gap between the microscale of IMEA and conventional bioconjugation techniques for enzyme immobilization, which leads to a series of challenges such as limited sensitivity, signal crosstalk, and high detection voltage. Here, we developed a novel method using carboxylated graphene oxide (cGO) to directionally couple the glutamate oxidase (GluOx) biomolecules onto the neural microelectrode to monitor glutamate concentration and electrophysiology in the cortex and hippocampus of epileptic rats under RuBi-GABA modulation. The resulting glutamate IMEA exhibited good performance involving less signal crosstalk between microelectrodes, lower reaction potential (0.1 V), and higher linear sensitivity (141.00 ± 5.66 nA µM-1 mm-2). The excellent linearity ranged from 0.3 to 68 µM (R = 0.992), and the limit of detection was 0.3 µM. For epileptic rats, the proposed IMEA sensitively obtained synergetic variations in the action potential (Spike), local field potentials (LFPs), and glutamate of the cortex and hippocampus during seizure and RuBi-GABA inhibition. We found that the increase in glutamate preceded the burst of electrophysiological signals. At the same time, both changes in the hippocampus preceded the cortex. This reminded us that glutamate changes in the hippocampus could serve as important indicators for early warning of epilepsy. Our findings provided a new technical strategy for directionally stabilizing enzymes onto the IMEA with versatile implications for various biomolecules' modification and facilitated the development of detecting tools for understanding the neural mechanism.

A Microelectrode Array Modified by PtNPs/PB Nanocomposites Used for the Detection and Analysis of Glucose-Sensitive Neurons under Different Blood Glucose States.

Hypoglycemia state damages the organism, and glucose-excited and glucose-inhibited neurons from the ventral medial hypothalamus can regulate this state. Therefore, it is crucial to understand the functional mechanism between blood glucose and electrophysiology of glucose-excited and glucose-inhibited neurons. To better detect and analyze this mechanism, a PtNPs/PB nanomaterials modified 32-channel microelectrode array with low impedance (21.91 ± 6.80 kΩ), slight phase delay (-12.7° ± 2.7°), high double layer capacitance (0.606 µF), and biocompatibility was developed to realize in vivo real-time detection of the electrophysiology activities of glucose-excited and glucose-inhibited neurons. The phase-locking level of some glucose-inhibited neurons elevated during fasting (low blood glucose state) and showed theta rhythms after glucose injection (high blood glucose state). With an independent oscillating ability, glucose-inhibited neurons can provide an essential indicator to prevent severe hypoglycemia. The results reveal a mechanism for glucose-sensitive neurons to respond to blood glucose. Some glucose-inhibited neurons can integrate glucose information input and convert it into theta oscillating or phase lock output. It helps in enhancing the interaction between neurons and glucose. Therefore, the research can provide a basis for further controlling blood glucose by modulating the characteristics of neuronal electrophysiology. This helps reduce the damage of organisms under energy-limiting conditions, such as prolonged manned spaceflight or metabolic disorders.

Injectable and fast gelling hyaluronate hydrogels with rapid self-healing ability for spinal cord injury repair.

Self-healing natural hydrogels still suffer from some issues such as unfit stiffness, poor healing efficiency, and lack of biocompatibility and hydrolytic stability, although they have been used to treat spinal cord injury (SCI). Herein, we develop the injectable, self-healing hyaluronate hydrogels based on multiple dynamic covalent bonds. The hydrogels exhibit fast gelation and excellent self-healing capability as well as injectability, favoring in situ formation for the hydrogels in target sites and maintaining their structural stability. Furthermore, the hydrogels are compatible with neural stem cells and various tissues and possess proper stiffness similar to nervous tissue. Interestingly, the hydrogel can induce neural differentiation of neural stem cells. In vivo experiment further illustrates that the hydrogels promote angiogenesis and remyelination as well as neuron regeneration, leading to the significant locomotor recovery of the SCI model rats. This injectable self-healing hyaluronic acid-based hydrogel is a potential candidate for nerve repair.

The burst of electrophysiological signals in the suprachiasmatic nucleus of mouse during the arousal detected by microelectrode arrays.

The neural mechanisms of torpor have essential reference significance for medical methods and long-term manned space. Changes in electrophysiology of suprachiasmatic nucleus (SCN) conduce to revealing the neural mechanisms from the torpor to arousal. Due to the lower physiology state during the torpor, it is a challenge to detect neural activities in vivo on freely behaving mice. Here, we introduced a multichannel microelectrode array (MEA) for real-time detection of local field potential (LFP) and action potential (spike) in the SCN in induced torpor mice. Meanwhile, core body temperature and behaviors of mice were recorded for further analysis. Platinum nanoparticles (PtNPs) and Nafion membrane modified MEA has a lower impedance (16.58 ± 3.93 kΩ) and higher signal-to-noise ratio (S/N = 6.1). We found that from torpor to arousal, the proportion of theta frequency bands of LFPs increased, spike firing rates rapidly increased. These results could all be characteristic information of arousal, supported by the microscopic neural activity promoting arousal in mice. MEA displayed real-time dynamic changes of neuronal activities in the SCN, which was more helpful to analyze and understand neural mechanisms of torpor and arousal. Our study provided a factual basis for the neural state in SCN of induced non-hibernating animals, which was helpful for the application of clinics and spaceflight.

Single-neuron detection of place cells remapping in short-term memory using motion microelectrode arrays.

Place cells establish rapid mapping relationships between the external environment and themselves in a new context. However, the mapping relationships of environmental cues to place cells in short-term memory is still completely unknown. In this work, we designed a silicon-based motion microelectrode array (mMEA) and an implantation device to record electrophysiological signals of place cells in CA1, CA3, and DG regions in the hippocampus of ten mice in motion, and investigated the corresponding place fields under distal or local cues in just a few minutes. The mMEA can expand the detection area and greatly lower the motion noise. Finding and recording place cells of moving mice in short-term memory is made possible by the mMEA. The place-related cells were found for the first time. Unlike place cells, which only fire in a particular position of the environment, place-related cells fire in numerous areas of the environment. Furthermore, place cells in the CA1 and CA3 have the most stable place memory for time-preferred single cues, and they fire in concert with place-related cells during short-term memory dynamics, whereas place cells in the DG regions have overlapping and unstable place memory in a multi-cue context. These results demonstrate the consistency of place cells in CA1 and CA3 and reflect their different roles in spatial memory processing during familiarization with new environments. The mMEA provides a platform for studying the place cells of short-term memory.

Grid cell remapping under three-dimensional object and social landmarks detected by implantable microelectrode arrays for the medial entorhinal cortex.

Grid cells with stable hexagonal firing patterns in the medial entorhinal cortex (MEC) carry the vital function of serving as a metric for the surrounding environment. Whether this mechanism processes only spatial information or involves nonspatial information remains elusive. Here, we fabricated an MEC-shaped microelectrode array (MEA) to detect the variation in neural spikes and local field potentials of the MEC when rats forage in a square enclosure with a planar, three-dimensional object and social landmarks in sequence. The results showed that grid cells exhibited rate remapping under social conditions in which spike firing fields closer to the social landmark had a higher firing rate. Furthermore, global remapping showed that hexagonal firing patterns were rotated and scaled when the planar landmark was replaced with object and social landmarks. In addition, when grid cells were activated, the local field potentials were dominated by the theta band (5-8 Hz), and spike phase locking was observed at troughs of theta oscillations. Our results suggest the pattern separation mechanism of grid cells in which the spatial firing structure and firing rate respond to spatial and social information, respectively, which may provide new insights into how the brain creates a cognitive map.

PtNPs/PEDOT:PSS-Modified Microelectrode Arrays Reveal Electrophysiological Activities of Different Neurons in Medial Amygdala of Mice Under Innate Fear.

The medial amygdala (MA) plays an important role in the innate fear circuit. However, the electrophysiological mechanism of MA for processing innate fear needs to be further explored. In this study, we fabricated microelectrode arrays (MEAs) with detecting sites arranged to match the location and shape of MA in mice and detected the electrophysiology in freely behaving mice under 2-methyl-2-thiazoline (2MT)-induced fear. The detection performance of MEA is improved by modifying metal nanoparticles and conductive polymers (PtNPs/PEDOT:PSS). After modification, the impedance magnitude and phase of electrodes were decreased to 27.0 ± 2.3 kΩ and -12.30 ± 0.52°, respectively, leading to a signal-to-noise ratio of 10. Its electrochemical stability and mechanical stability were also verified by cyclic voltammetry (CV) sweeping and ultrasonic vibration. MEAs were then implanted into the MA of mice, and the electrophysiology and behavioral characteristics were synchronously recorded and analyzed. The results showed that 2MT induced strong defensive behaviors in mice, accompanied by increases in the average spike firing rate and local field potential (LFP) power of MA neurons. According to principles commonly applied to cortical extracellular recordings, the recorded neurons are divided into two classes based on waveforms. Statistics showed that about 37% of type 1 neurons (putative GABAergic neurons) and 87% of type 2 neurons (putative glutamatergic neurons) were significantly activated under innate fear. At the same time, the firing rate of some activated neurons had a good linear correlation with the freezing rate.

Neuronal Electrophysiological Activities Detection of Defense Behaviors Using an Implantable Microelectrode Array in the Dorsal Periaqueductal Gray.

Defense is the basic survival mechanism of animals when facing dangers. Previous studies have shown that the midbrain periaqueduct gray (PAG) was essential for the production of defense responses. However, the correlation between the endogenous neuronal activities of the dorsal PAG (dPAG) and different defense behaviors was still unclear. In this article, we designed and manufactured microelectrode arrays (MEAs) whose detection sites were arranged to match the shape and position of dPAG in rats, and modified it with platinum-black nanoparticles to improve the detection performance. Subsequently, we successfully recorded the electrophysiological activities of dPAG neurons via designed MEAs in freely behaving rats before and after exposure to the potent analog of predator odor 2-methyl-2-thiazoline (2-MT). Results demonstrated that 2-MT could cause strong innate fear and a series of defensive behaviors, accompanied by the significantly increased average firing rate and local field potential (LFP) power of neurons in dPAG. We also observed that dPAG participated in different defense behaviors with different degrees of activation, which was significantly stronger in the flight stage. Further analysis showed that the neuronal activities of dPAG neurons were earlier than flight, and the intensity of activation was inversely proportional to the distance from predator odor. Overall, our results indicate that dPAG neuronal activities play a crucial role in controlling different types of predator odor-evoked innate fear/defensive behaviors, and provide some guidance for the prediction of defense behavior.