Dual-mode Sensor Research Articles

Dual-mode fluorescence and electrochemiluminescence sensors based on Ru-MOF nanosheets for sensitive detection of apoE genes.

A fluorescence-electrochemiluminescence (FL-ECL) dual-mode sensor for apoE gene detection has been developed, leveraging the unique properties of ruthenium metal organic framework nanosheets (RuMOFNSs). The system utilizes the quenching effect of the Ru(bpy)32+ ECL signal by ferrocene, leading to the synthesis of a multi-electron electrical signal marker, bisferrocene. By immobilizing the P-DNA on RuMOFNSs, bisferrocene quenches both FL and ECL signals. The addition of T-DNA and the consequent formation of double-stranded DNA enable the ExoIII enzyme to excise the bisferrocene fragment, restoring the signals. The sensor demonstrates wide detection linear ranges (1 fM to 1 nM for FL and 0.01 fM to 10 pM for ECL) and remarkable sensitivity (0.048 fM for FL and 0.016 fM for ECL). The dual-mode design offers enhanced reliability through a self-correction feature, reducing false positives. Compared to single-mode sensors, the dual-mode sensor shows significant advantages. Real-world testing confirms the sensor's capacity for robust detection in actual samples, underscoring its promising application in early disease diagnosis. This innovative approach opens up avenues for multi-signal response sensors, offering significant potential for diagnostic technologies.

A dual-mode homogeneous electrochemical-colorimetric biosensing sensor for carcinoembryonic antigen detection based on a microfluidic paper-based analysis device.

Dual-mode-based sensors have drawn a lot of interest due to their high accuracy and sensitivity compared to single-response systems. A simple electrochemical and colorimetric dual-mode sensor based on enzyme-linked immunosorbent assay (ELISA), without complex electrode surface modification, was developed for accurate and sensitive detection of carcinoembryonic antigen (CEA). The target CEA is recognized by an antibody coupled to horseradish peroxidase (HRP), which then oxidizes the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to generate both a colorimetric and an electrochemical signal. A paper-based analysis device (μPAD) with dual-mode homogeneous sensing microfluidic was created; three paper-based detection areas for colorimetric testing, and a two-electrode embedded detection area for electrochemical testing. When applying colorimetric analysis technology, the linear range of CEA detection is 0.6-40 ng mL-1, and the limit of detection (LOD) is 0.2 ng mL-1. The linear range is 0.1-40 ng mL-1 and the LOD is 0.03 ng mL-1 by applying electrochemical analysis. The visibility and intuitiveness of colorimetry provide a reference for higher sensitivity and quick response of the electrochemical method. A smartphone application (APP) was also developed to realize the dual extraction of colorimetric signals. The colorimetric detection system based on ELISA can provide a new path for the development of electrochemical sensing and makes it have inherent self-verification and self-correction functions and is expected to provide more reliable and accurate detection results.

A dual-mode wearable sensor with electrophysiological and pressure sensing for cuffless blood pressure monitoring

A wearable dual-mode sensor is created by integrating liquid metal into an ionogel. It can simultaneously monitor both the electrocardiogram and arterial pulse to simplify the measurement of the pulse transit time and thus the blood pressure.

Synthesis and application of optical silver nanoparticles capped carbon dots as dual-mode sensors for trivalent chromium ions in dietary supplements

A facile method for trivalent chromium (Cr3+) ion determination using optical silver nanoparticles capped carbon dots (Ag@CDs) was developed. The optical responses via absorption and fluorescence of Ag@CDs in the presence of Cr3+ ion were detected. The nanocomposite showed maximum absorption wavelength at 406.0 nm, while emission wavelength appeared at 526.0 nm when excited at 406.0 nm. Optimal conditions for the Ag@CDs activity on Cr3+ ion detection were at pH 6, volume ratio between Ag@CDs and Cr3+ ion of 1.0:4.0, and reaction time of 20 min. The linearity range of the detection was 0.1–10.0 mg/L. In the absorption mode, the limit of detection (LOD) and limit of quantification (LOQ) were 0.10 mg/L and 0.31 mg/L, respectively. The fluorescence mode of detection showed LOD and LOQ of 0.06 mg/L and 0.18 mg/L, respectively. The dual-mode sensor was applied for Cr3+ ion quantification in dietary supplement samples because it is an essential micronutrient and widely used as supplement products. The recovery study of the spiked sample extracts was in the range of 96.86–103.05 %. The results showed good agreement with those from a conventional method of atomic emission spectrometry. The optical changing mechanism of the nanocomposite could be explained by the electron transfer from Ag@CDs to Cr3+.

Design of a multidimensional data collection system based on DRS4 scheme

A high-speed data acquisition system based on DRS4 waveform digitization is designed to meet the requirements of high sampling rate, multi-parameter measurements, and long-distance transmission in some particle physics experiments. The system consists of a waveform digitization front-end board, a high-speed data transmission board, and an upper computer software. Test results show that the system has a high data transmission rate and a low BER and that the collected data can reconstruct and restore the input signal waveform well. In addition, we have analyzed the single-electrode dual-mode sensor, excitation signal generation module, resistor/capacitor conversion circuit, and phase-sensitive demodulation unit in the system. The experiments show that the system is stable in operation, flexible in use, and can significantly extend the measurement range.

A colorimetric and fluorescent dual-mode sensor based on bifunctional G-quadruplex-hemin complex for the determination of Pb2+

Due to the threat of lead pollution to health, environmental and food safety, developing simple and fast detection methods is highly required. Whereas, traditional single-mode probe suffers from limited application scenario. In this study, a colorimetric and fluorometric dual-mode probe for Pb2+ determination was constructed by using bifunctional G-quadruplex-hemin complex. In this dual-mode probe, enzyme strand and substrate strand of 8–17 DNAzyme are labeled with G-quadruplex-hemin complex and fluorophore, respectively. In the absence of Pb2+, the self-assembly of enzyme strand and substrate strand inhibits intrinsic mimic peroxidase of G-quadruplex-hemin complex by base-pairing, which also quench the fluorescence via in proximity effect. When the DNAzyme is activated by Pb2+, the quenched fluorescence is restored as well as the inherent peroxidase mimetic activity, leading to dual signal output. Under optimal conditions, this dual-mode probe exhibit a good linear relationship between logarithm of Pb2+ concentration and signal difference within the range from 1.5 nM to 20 nM and 0.5 nM to 10 nM for colorimetric and fluorescence mode, respectively. The detection limits for the corresponding mode were estimated to be 1.29 nM and 0.16 nM, respectively. This dual-mode probe also successfully applied for the spiked river water assay with satisfactory recovery in the range of 93.2 %–115.3 %. This work paves a new way for DNAzyme based dual-mode probe construction.

A dual-mode fiber-shaped flexible capacitive strain sensor fabricated by direct ink writing technology for wearable and implantable health monitoring applications

Flexible fiber-shaped strain sensors show tremendous potential in wearable health monitoring and human‒machine interactions due to their compatibility with everyday clothing. However, the conductive and sensitive materials generated by traditional manufacturing methods to fabricate fiber-shaped strain sensors, including sequential coating and solution extrusion, exhibit limited stretchability, resulting in a limited stretch range and potential interface delamination. To address this issue, we fabricate a fiber-shaped flexible capacitive strain sensor (FSFCSS) by direct ink writing technology. Through this technology, we print parallel helical Ag electrodes on the surface of TPU tube fibers and encapsulate them with a high dielectric material BTO@Ecoflex, endowing FSFCSS with excellent dual-mode sensing performance. The FSFCSS can sense dual-model strain, namely, axial tensile strain and radial expansion strain. For axial tensile strain sensing, FSFCSS exhibits a wide detection range of 178%, a significant sensitivity of 0.924, a low detection limit of 0.6%, a low hysteresis coefficient of 1.44%, and outstanding mechanical stability. For radial expansion strain sensing, FSFCSS demonstrates a sensitivity of 0.00086 mmHg−1 and exhibits excellent responsiveness to static and dynamic expansion strain. Furthermore, FSFCSS was combined with a portable data acquisition circuit board for the acquisition of physiological signals and human‒machine interaction in a wearable wireless sensing system. To measure blood pressure and heart rate, FSFCSS was combined with a printed RF coil in series to fabricate a wireless hemodynamic sensor. This work enables simultaneous application in wearable and implantable health monitoring, thereby advancing the development of smart textiles.

Ratio-fluorescent and naked-eye visualized dual-channel sensing strategy for Cu2+ and alkaline phosphatase activity assay.

The levels of Cu2+ and alkaline phosphatase (ALP) are the important indicators of the developed stage of the relative diseases. Herein, a binary ratio-fluorescent and smartphone-assisted visual strategy basing on 4'-aminomethyl-4, 5', 8-trimethylpsoralen (AMT) and the oxidation of o-phenylenediamine was developed. Under the action of Cu2+, the fluorescent molecule, 3-diaminophenazine (DAP) formed which can act as a fluorescent acceptor of the ratio-fluorescent sensor. The emission spectrum of AMT overlapped with the excitation spectrum of DAP and, thus, it can act as the fluorescent donor of the ratio-fluorescent sensor. With the increasing concentration of Cu2+ and ALP, the fluorescent intensity of AMT decreased and the fluorescent intensity of DAP increased. The dual-emission reverse change ratio-fluorescent sensor realized the sensitive detection Cu2+ and ALP with the detection limits of 2nM and 0.03 U/mL, respectively. In addition, the acceptable recoveries were obtained when the Cu2+ and ALP in spiked samples were detected. Furthermore, the relative activity of ALP was assessed by increasing the concentrations of the inhibitor Na3VO4 and IC50 of 25μM was obtained. Importantly, the target concentration-dependent color change of DAP allowed us to utilize R/B ratio values to design the smartphone-assisting visual detection model of Cu2+ and ALP activity with the detection limits of 0.1μM and 0.18 U/mL. This simple, flexible, dual-mode sensor strategy has a potential for disease diagnosis and drug screening.

Photoluminescence-Electrochemiluminescence Dual-Mode Sensor Arrays for Histidine and Its Metabolite Discrimination and Disease Identification.

Histidine (His) and its metabolite analysis is significant due to their vital roles in the diagnosis of diseases. In practical applications, simple and effective detection and discrimination of these metabolic species are still a great challenge due to their highly similar structures. Herein, photoluminescence (PL)-electrochemiluminescence (ECL) dual-mode sensor arrays consisting of a series of sensing elements were proposed for simultaneous quantitation and accurate discrimination of His and its four key metabolites (including histamine, imidazole-4-acetic acid, N-acetylhistamine, and imidazole propionate). The sensing elements of these sensor arrays were constructed by employing two solvent iridium(III) complexes ([Ir(pbz)2(DMSO)Cl] and [Ir(ppy)2(DMSO)Cl], pbz = 3-(2-pyridyl)benzoic acid, ppy = 2-phenylpyridine) with excellent PL and ECL performances as cross-responsive sensing units. Based on diverse coordination abilities of the two complexes with the imidazole group of the five targets, PL and ECL responses of each sensing unit can be enhanced to various degrees, which generate unique fingerprint patterns for the corresponding targets. Through principal component analysis, the multifarious patterns (two-, three-, and four-element sensor arrays) can be transformed into simple visualization modes, from which His and its four key metabolites can be effectively discriminated against each other. Moreover, the quantitation of an individual metabolic species at different concentrations and the recognition of the mixtures with different ratios were also accurately achieved. Notably, His and its four key metabolites in urine can also be successfully discriminated by the as-fabricated sensor arrays, and the patients with kidney diseases can be identified clearly, providing a promising way for disease diagnosis.

Stretchable ionic composites for strain-insensitive dual-mode pressure and proximity sensors

Simultaneously sensing pressure and proximity allows for the detection of contact pressure and the distance of approaching objects. This dual functionality ensures precise human–machine interactions and real-time adaptive responses to dynamic environments, proving it useful in human–machine interfaces, robots, and wearable devices. In this study, we introduce a highly stretchable and strain-insensitive pressure and proximity sensor capable of maintaining its electrical properties under mechanical deformations, achieved by establishing a continuous conductive pathway through an ionic bridge between conductive fillers. The strain-insensitive and stretchable composite exhibits ΔR/R0 of 0.024 under stretching up to 140% after 1,000 times. When the strain-insensitive composite is combined with a micro-patterned insulating layer, the resulting piezoresistive pressure sensors exhibit uniform pressure sensing capability even under mechanical deformations of tensile strain (∼50%) and bending curvature (1.3 cm−1). Moreover, our pressure sensor can be functioned as a capacitive-type proximity sensor capable of identifying material, shape, and distance of approaching objects with high sensitivity (capacitance change (ΔC/C0) of −0.88). As a proof-of-concept demonstration, our dual-mode pressure sensor with a multichannel array enables real-time monitoring of contact/noncontact pressure distribution, including intensity, shape, and proximity regardless of mechanical interference and surface roughness. Our approach to achieving high sensitivity and selectivity for desired contact/noncontact stimuli independent of mechanical interferences offers a novel platform for practical sensor applications.

Core-Satellite Nanoassemblies as SPR/SERS Dual-Mode Plasmonic Sensors for Sensitively Detecting Ractopamine in Complex Media.

Highly sensitive and reliable detection of β-adrenergic agonists is especially necessary due to the illegal abuse of growth-promoting feed additives. Here, we develop a novel surface plasmon resonance/surface-enhanced Raman scattering (SPR/SERS) dual-mode plasmonic sensor based on core-satellite nanoassemblies for the highly sensitive and reliable detection of ractopamine (RAC). The addition of RAC results in the decomposition of core-satellite nanoassemblies and consequently changes the Rayleigh scattering color of dark-field microscopy (DFM) images and the Raman scattering intensity of SERS spectra. The excellent sensitivity, specificity, and uniformity of this strategy were confirmed by detecting RAC in various complex media in the farm-to-table chain, and the limit of detection (LOD) was 0.03 ng/mL in an aqueous solution. In particular, the convenient access to livestock sewage not only ensures animal welfare but also provides great convenience for the market regulation of β-agonists. The success of our on-site strategy only with a portable Raman device promises great application prospects for β-agonist detection.

Serpentine liquid electrode based Dual-mode skin Sensors: Monitoring biomechanical movements by resistive or triboelectric mode

Flexible and stretchable electrodes are crucial components for wearable electronic devices. Herein, a serpentine liquid electrode based dual-mode skin sensors (SLEDSS) that leverages a highly deformable and serpentine liquid electrode is developed. The functional carboxylated multi-walled carbon nanotubes / Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (MWCNT-COOH / PEDOT: PSS) network structure endows the SLEDSS with a stable linear change in resistance. Additionally, a solid–liquid double electric layer generated between the solid surface and liquid electrode facilitates a higher triboelectric output performance. As a result, the SLEDSS features dual-modal sensing capabilities, including both resistive and triboelectric modes. The flowability of the liquid electrode enables it to fully adapt to different types of deformation, thereby allowing SLEDSS to effectively collect energy in different forms of movement, such as tapping, stretching, bending, twisting, and unpredictable transformations based on practical applications. SLEDSS can maintain its performance even at up to 550.32% strain, displaying a monotonically increasing relationship between the stretchable length and open-circuit voltage. Finally, the SLEDSS is applied as a wearable power source and self-powered sensor for monitoring biomechanical movements, the excellent stretchable performance and ultra-high sensitivity to mechanical stimulation provided by the SLEDSS offer new prospects for self-powered sensors.

Development of a fluorometric and colorimetric dual-mode sensing platform for acid phosphatase assay based on Fe3+ functionalized CuInS2/ZnS quantum dots

BackgroundThe spectral dual-mode response towards analyte has been attracted much attention, benefiting from the higher detection accuracy of such strategy in comparison to single signal readout. However, the currently reported dual-mode sensors for acid phosphatase (ACP) activity are still limited, and most of them more or less exist some deficiencies, such as complicated construction procedure, high-cost, poor biocompatibility, aggregation-caused quenching and limited emission capacity. ResultsHerein, we employed Fe3+ functionalized CuInS2/ZnS quantum dots (CIS/ZnS QDs) as nanosensor to develop a novel fluorometric and colorimetric dual-mode assay for ACP activity, combing with ACP-triggered hydrolysis of ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA). The Fe3+ binding to CIS/ZnS QDs can be reduced into Fe2+ during the determination, resulting in the dramatically weakened photoinduced electron transfer (PET) effect and the disappearance of competition absorption. Thus, a highly sensitive ACP assay in the range of 0.22–12.5 U L−1 through fluorescence “turn-on” mode has been achieved with a detection of limit (LOD) of 0.064 U L−1. Meanwhile, the ACP activity can also be quantified by spectrophotometry based on the chromogenic reaction of the formed Fe2+ with 1,10-phenanthroline (Phen). Moreover, the designed nanosensor with good biocompatibility was successfully applied to image and monitor the ACP levels in living cells. SignificanceWe believe that the proposed method has remarkable advantages and potential application for ACP assay in terms of the high accuracy, simplicity, low cost, as well as its adequate sensitivity.

A flexible dual-mode triboelectric sensor for strain and tactile sensing toward human-machine interface applications

In recent years, there has been significant progress in the development of flexible sensors for human-machine interfaces. However, the triboelectric principle, especially which based on sliding mode, is relative rarely applied to flexible strain sensors. Therefore, a novel triboelectric flexible stretchable sensor has been designed with a simple structure, convenient fabrication process, and effective response to various strain signals (Within the range of 0%−200%, the average sensitivity is 49.07 mV per 1% strain). This sensor operates in a new triboelectric working mode: variable charge density mode (VCD mode). Furthermore, the sensor can also be utilized for tactile sensing in vertical contact-separation mode without any structural modifications. Based on this strain-tactile dual-mode flexible triboelectric sensor (STDFTS), its applications for human-machine interface have been explored: gesture recognition (recognition accuracy of five gestures reaches 99.4%) based on tactile sensing and mouse replacement based on dual working modes. The STDFTS proposed in this article provides a new alternative solution for human-machine interfaces, greatly expanding the application scenarios of triboelectricity. The sensor's innovative design and dual-mode functionality open up new avenues for research and development in the field of triboelectric nanogenerator, flexible sensors and human-machine interaction.

Silver metallization-triggered liposome-embedded AIE fluorophore for dual-mode detection of biogenic amines to fight food freshness fraud.

To combat food freshness fraud, it is urgent to develop a method which could realize the detection of biogenic amines (BAs) present in food. In our study, we developed a colorimetric and ratiometric fluorescence dual-mode sensor which integrated with silver metallization-based response system of AIE liposome+OPD+RSM+Ag+ toward BAs in foods for fighting freshness fraud. With the hydrolysis from the alkaline of BAs to resorcinol monoacetate (RSM), the production resorcinol (RS) could metallize silver ion (Ag+) to silver atoms (Ag0) which could lead to a BAs concentration-dependent decrease of the oxidation product 2,3-diaminophenothiazine (DAP) of Ag+ to o-phenylenediamine (OPD). As a result, the dual-mode sensor has a low detection limit and wide linear range in the spiked detection of soy products, pork and milk samples for BAs. Thus, providing a reliable method for food safety and forestalling food freshness fraud.

ICP-MS and fluorescence dual-mode detection of ZIKV-RNA based on quantum dot labeling with hybridization chain reaction

The detection of Zika virus (ZIKV) is of great significance to human life and health. Herein, we presented an ICP-MS and fluorescent dual-mode sensor for quantitative analysis of Zika virus RNA fragments (ZIKV-RNA), which employed quantum dots (QDs) as signal tags and combined with hybridization chain reaction (HCR). The dual-mode sensor realized cross-checking of the analysis results and improved the assay accuracy. Firstly, the single-stranded DNA (ssDNA) was anchored on the surface of magnetic beads (MBs). Afterward, HCR was conducted with probe DNA-CdSe quantum dots conjugates (pDNA-QDs) and link DNA (lDNA), producing the MBs-ssDNA-[pDNA-QDs-lDNA]n conjugates. In the presence of target ZIKV-RNA, a strand displacement reaction occurred, leading to the dissociation of the [pDNA-QDs-lDNA]n labels from the conjugates into the solution. Finally, the signal intensity was detected using ICP-MS and fluorescence analysis, with achieved limits of detection of 131 pM and 152 pM, respectively. The inter-assay RSD values of fluorescence and ICP-MS were 3.94 % and 4.26 % at 10 nM level, respectively, showing that the method had good precision. This method showed high selectivity and was applied to the analysis of biological fluids. There was no significant difference between the results of ICP-MS modes and fluorescence mode. This method offers a new strategy for sensitivity analysis of ZIKV-RNA and exhibits promise in clinical applications for diagnosis.

Colorimetric and fluorescence dual-mode pH sensor based on nitrogen-doped carbon dots and its diverse applications.

A dual-mode pH sensor based on nitrogen-doped carbon dots (N-CDs) with the source of o-phenylenediamine and tryptophan has been constructed. Under the stimulation of pH, the N-CDs exhibited prominent both color and fluorescence changes, leading to the rarely discovered colorimetric and fluorescent dual-readouts for the evaluation of pH. The mathematic relationship was established between pH and fluorescence intensity of N-CDs, and between pH and the UV-Vis absorbance ratio at 630 nm and 488 nm of N-CDs, respectively, over a quite broad pH range of 2.2 to 12.0. Multiple techniques are used to explore the dual-mode pH-responsive mechanism, and the preliminary explanation is put forward. The experimental results show that the N-CDs have visualized pH sensing applicability for actual samples, including various water samples and HeLa cell. Furthermore, the N-CD ink is developed for successful information encryption and anti-counterfeiting. This work might provide valuable insights into the sensing mechanism of CDs, and the application potential of CDs in broader fields.

Silver nanocluster-based colorimetric/fluorimetric dual-mode sensor for the detection of bromide and sulfite in waters and wastewaters

In this work, the development of a fluorimetric/colorimetric dual-mode nanosensor for the determination of sulfite and fluorimetric determination of bromide involving silver nanoclusters (AgNCs) is reported. SO2 and Br2 were found to significantly modify the optical properties of AgNCs. Particularly, both volatiles weakened the fluorescence of AgNCs, whereas a color change from nearly colorless to yellowish/brown upon exposure of AgNCs to SO2. Accordingly, three smartphone-based optical assays were devised for sulfite and bromide determination, involving in situ volatile generation and enrichment/trapping of the selectively formed volatiles by AgNCs confined in a droplet and exposed to the headspace above the sample. A hydrophobized cellulose substrate acting as drop holder enabled integrating both the enrichment and the subsequent smartphone-based optical detection in a straightforward manner. Smartphone-based digitization of the enriched AgNCs microdrops and subsequent image processing using a smartphone and its integrated App, respectively, were used for quantitative purposes. Under optimal conditions, limits of detection (LODs) of 1.1 µM and 1.5 µM were achieved for the fluorimetric determination of sulfite and bromide, respectively, whereas sulfite was alternatively determined by colorimetric readout, yielding a LOD of 37.0 µM. The repeatability, expressed as relative standard deviation, was found to be in the range of 5.1–5.9 % in all cases (N = 8). The applicability of the method was demonstrated in aqueous samples of increasing complexity, with recoveries in the range 91–109 %. In addition, the responsiveness of AgNCs to SO2 and Br2 rendered them suitable for the monitoring of bromide and sulfite in increasingly relevant advanced reduction processes such as the UV/sulfite system, as demonstrated in this work.

Dual-mode sensor based on GO-SELEX screening of aptamer for detecting cefapirin antibiotic residues in milk

The extensive use of cefapirin (CP) in milk has caused various health issues, resulting in an urgent need for an efficient assay for its detection. This study aimed to perform a colorimetric/fluorescence dual-mode assay based on graphene oxide–assisted systematic evolution of ligands by exponential enrichment (GO-SELEX) in vitro screening method for detecting CP aptamers. The aptamer (Apt22) had a high affinity (Kd = 13.818 ± 1.405 nM), with only 33 bases. Hence, we designed the G-quadruplex (G4) into a hairpin structure complemented by the shear effect of Exo III, and constructed a colorimetric/fluorescent dual-mode sensor. A colorimetric signal was generated using 3,3′,5,5′-tetramethylbenzidine discoloration catalyzed by a DNA-mimicking enzyme constructed from G4 and hemin. The formation of G4 implied that the hairpin structure was disrupted and the FAM and BHQ at the ends of it were separated, thus generating a fluorescent signal. Under optimal experimental conditions, the detection limits were 0.0168 and 0.0136 μM when the linear ranges of the colorimetric and fluorescent aptasensors were 1–8 μM and 0.9–2.3 μM. The sensor had high specificity and repeatability. It combined the advantages of visual colorimetric and fluorescence precision detection, providing a new approach to the practical monitoring of CP in milk.

Dual-mode Janus Structural-Color films toward an integrated sensing device with synergistic optical and electrical outputs

Real-time sensing technologies have shown significant importance for environmental management, chemical monitoring, and industrial production. Current chemical sensors with high sensing performances toward gases or liquids have been realized individually; however, a simultaneous detection of targets in the both forms along with a low detection limit and a wide detection range remains a big challenge. Here, we present a novel switchable dual-mode Janus-structured sensor with integrated structural colors and electrical conductivity for chemical detection. The photonic layer formed by the self-assembly of cellulose photonic crystals shows highly selective responses to high-concentration targets via the color-changing channel, while the electrically conductive layer generated by the formation of carbon nanotube networks demonstrates target perceptions at low concentration and even ppm levels. Notably, the integrated sensor is further designed as a wearable sensing system for chemical monitoring in different application scenarios. These findings offer new thinking to design switchable multi-mode sensors for environmental and industrial surveillance.