Antenna Effect Research Articles

A dual-response ratiometric fluorescent sensor for oxytetracycline determination in milk and mutton samples

Owing to the adverse effects of oxytetracycline (OTC) residues on human health, it is of great importance to construct a rapid and effective strategy for OTC detection. Herein, we developed a dual-response fluorescence sensing platform based on molybdenum sulfide quantum dots (MoS2 QDs) and europium ions (Eu3+) for ratiometric detection of OTC. The MoS2 QDs, synthesized through an uncomplicated one-step hydrothermal approach, upon OTC integration into the MoS2 QDs/Eu3+ sensing system, exhibit a significant quenching of blue fluorescence due to the inner filter effect (IFE), simultaneously enhancing the distinct red emission of Eu3+ at 624 nm, a phenomenon attributed to the antenna effect (AE). This sensor demonstrates exceptional selectivity and sensitivity towards OTC, characterized by a linear detection range of 0.2–10 μM and a notably low detection limit of 2.21 nM. Furthermore, we achieved a visual semi-quantitative assessment of OTC through the discernible fluorescence color transition from blue to red under a 365 nm ultraviolet lamp. The practical applicability of this sensor was validated through the successful detection of OTC in milk and mutton samples, underscoring its potential as a robust tool for OTC monitoring in foodstuffs to safeguard food safety.

Dual-Ligand Europium-Organic Gels as a Highly Efficient Anodic Annihilation Electrochemiluminescence Emitter for Ultrasensitive Detection of MicroRNA.

In this study, a novel europium dual-ligand metal-organic gel (Eu-D-MOGs) with high-efficient anodic annihilation electrochemiluminescence (ECL) was synthesized as an ECL emitter to construct a biosensor for ultrasensitive detection of microRNA-221 (miR-221). Impressively, compared to the ECL signal of europium single-ligand metal-organic gels (Eu-S-MOGs), the ECL signal of Eu-D-MOGs was significantly improved since the two organic ligands could jointly replace the H2O and coordinate with Eu3+, which could remarkably reduce the nonradiative vibrational energy transfer caused by the coordination between H2O and Eu3+ with a high coordination demand. In addition, Eu-D-MOGs could be electrochemically oxidized to Eu-D-MOGs•+ at 1.45 V and reduced to Eu-D-MOGs•- at 0.65 V to achieve effective annihilation of ECL, which overcame the side reaction brought by the remaining emitters at negative potential. This benefited from the annihilation ECL performance of the central ion Eu3+ caused by its redox in the electrochemical process. Furthermore, the annihilation ECL signal of Eu3+ could be improved by sensitizing Eu3+ via the antenna effect. In addition, combined with the improved rolling circle amplification-assisted strand displacement amplification strategy (RCA-SDA), a sensitive biosensor was constructed for the sensitive detection of miR-221 with a low detection limit of 5.12 aM and could be successfully applied for the detection of miR-221 in the lysate of cancer cells. This strategy offered a unique approach to synthesizing metal-organic gels as ECL emitters without a coreactant for the construction of ECL biosensing platforms in biomarker detection and disease diagnosis.

System design of a microstrip antenna by dimension and substrates optimization

The microstrip antennas matured and improved over the last 25 years. Throughout these years, the limitations, and specifications of the said antennas have been overcome and significantly improved. Known to be lowprofile, suitable for mobile, and lightweight, these microstrip antennas are the focus of this research. In this paper, the researchers designed a microstrip antenna with varying lengths and substrates. They tested the changes and the effects in microstrip antennas of different lengths, along with altering substrates. To verify the differences, the researchers compared the performance parameters maximum gain (dBi), minimum gain (dBi), and S11 graph on each tested length and changed substrate. The rough set theory was used to determine the optimal design via MATLAB. From there, the researchers analyzed the results gathered and drew their respective conclusions. Additionally, they saw and compared each data result to know what antenna has the best performance parameters. From the results, a change in the dimension will result in a decrease in the said performance parameters. Furthermore, the change in substrate thickness also diminishes these changes.

A novel sparse-based approach for joint radio frequency fingerprint and channel estimation

Radio Frequency Fingerprint (RFF) plays a pivotal role in specific emitter identification (SEI) and enhancing the physical layer security of wireless networks. However, past research on RFF extraction has encountered significant challenges, including algorithm instability in the presence of multi-path channels, disparities between actual RFF and proposed models, and the need to compensate for receiver RFF. In this study, we introduce an innovative algorithm designed to simultaneously estimate the transmitter's RFF and the non-line-of-sight (NLOS) channel state in the presence of receivers’ antenna effect. Moreover, we introduce the transmitter antenna feeding current as a modified RFF, accounting for transimtter components such as power amplifier (PA) nonlinearity, in-phase quadrature (IQ) modulator imbalance. Our approach commences with an exploration of wave propagation theory fundamentals, followed by a transformation of the inverse scattering equations into linear equations for joint channel and RFF estimation. Due to the non-convex nature of the derived equation, we employ the sparse lift method to render the problem convex. Leveraging the sparsity of channel coefficients, we devise a compressive sensing linear solution, denoted as the sparse-based approach for joint (SBJ) RFF and channel estimator. Additionally, we propose a calibration method to mitigate the effect of the receiver antennas on the estimated RFF of the transmitter. Through simulation, we demonstrate a 10 dB enhancement in RFF estimation accuracy compared to existing methods. Furthermore, our results indicate that the SBJ algorithm remains robust when faced with the combined effect of transmitter components, whereas previous models exhibit diminished precision as additional component effects are considered.

Reabsorption‐Free Scintillating Hetero‐Ligand MOF Crystals Activated by Ultrafast Energy Transfer

AbstractFast photoluminescence and scintillation with a Stokes shift larger than 1 eV is achieved in hetero‐ligand metal–organic framework (MOF) crystals comprising inorganic linking nodes and fluorescent conjugated ligands. By finely engineering the MOF composition with the use of ligands with strictly complementary emission and absorption properties and highly delocalized molecular electronic orbitals, the singlet excitons diffusion is enhanced through the ligand framework, fully exploiting both Förster and Dexter energy transfer mechanisms. This allows for the sensitization of energy acceptor ligand fluorescence by ultrafast non‐radiative energy transfer with a rate up to the THz range. This efficient antenna effect instantly activates the MOF scintillation with a Stokes shift as large as 1.3 eV in the blue spectral range, matching the highest sensitivity spectral window of the best photodetector available. This is obtained using a minimal doping level of the energy acceptor species, with a consequent elimination of emission re‐absorption that allows the achievement of a 500% increment of the MOFs scintillation efficiency and the detection of the radioactive krypton isotope 85Kr from the gas phase with an improved sensitivity compared with the reference material.

CsPbBr3 PQDs in EuAPO-5 zeolite: Highly stable fluorescent-traffic-light sensor for point-of-care response of tetracycline and temperature

Fluorescent point-of-care (POC) sensors with specific target recognition capability through signaling mechanisms have promising applications in areas such as environmental monitoring and food detection. Herein, a solvent-free method was developed to prepare a novel POC sensor based on dual-luminescent CsPbBr3@EuAPO-5 composite that enabled the multiple sensing of tetracycline (TC) and temperature in a unique fluorescent-traffic-light manner. Benefiting from the confinement effect of EuAPO-5 zeolite, the CsPbBr3 perovskite quantum dots (PQDs) exhibits extraordinary luminescent stability even soaking in water for 30 days. During TC detection, the effective absorbed energy transfer from TC to Eu3+ in EuAPO-5 zeolite through the antenna effect enhances the red emission of Eu3+, and meanwhile a internal filtering effect (IFE) between the TC molecule and CsPbBr3 PQDs results in the green emission quenching of CsPbBr3. Combining the colorimetric determination using a smartphone-based analysis application (APP), the CsPbBr3@EuAPO-5 can serve as a portable POC sensor for TC monitoring in aqueous solution with a low detection limit of 0.013 µM in a linear range of 0–140 µM. Besides, ratiometric temperature sensing behavior of CsPbBr3@EuAPO-5 for high temperature warning in a fluorescent-traffic-light manner was also achieved, boosting a high sensitivity of 27.63 % K-1 (at 383 K) and a temperature resolution greater than 0.0035 K in 293–383 K. This work provides a novel bifunctional CsPbBr3 PQDs based sensor for reliable and visual detection of TC concentration and temperature, laying the foundation for the development of high-quality POC sensors with exceptional sensitivity and practicality.

Lanthanide doped metal−organic framework: novel turn-on fluorescent sensing of iodide in kelp and seawater samples

An effective fluorescence sensor was developed for iodide detection, with copper-based metal−organic frameworks (Cu-BTC) into which Tb3+ was doped by post modification. Tb@Cu-BTC manifested the characteristic emission of Tb3+ resulted from efficient sensitization through antenna effect, which was further exploited as a “turn-on” fluorescence probe to determinate iodide in aqueous solution. The sensor exhibited two great linear ranges of 12.5 ∼ 40 μM and 40 ∼ 160 μM, with a good limit of detection of 4.7 μM for iodide. These results showed that Tb@Cu-BTC exhibited high selectivity, excellent stability and great anti-interference capability for iodide monitoring. The possible mechanism could be object-induced luminescence. In addition, recovery experiments have been carried out to determine iodide in tap water and sea water. This method based on Tb@Cu-BTC could also be potentially employed to determinate iodide in other samples.

Merging Dual Antenna Effect with Target-Insensitive Behavior in Bimetal Biligand MOFs to Form Efficient Internal Reference Signal: Color Tonality-Ratiometric Designs

Merging Dual Antenna Effect with Target-Insensitive Behavior in Bimetal Biligand MOFs to Form Efficient Internal Reference Signal: Color Tonality-Ratiometric Designs

A novel fluorescence platform for specific detection of tetracycline antibiotics based on [MQDA-Eu3+] system

Tetracycline antibiotics (TCs) are extensively used in clinical medicine, animal husbandry, and aquaculture because of their cost-effectiveness and high antibacterial efficacy. However, the presence of TCs residues in the environment poses risks to humans. In this study, an inner filter effect (IFE) fluorescent probe, 2,2′-(ethane-1,2-diylbis((2-((2-methylquinolin-8-yl)amino)-2-oxoethyl)azanediyl))diacetic acid (MQDA), was developed for the rapid detection of Eu3+ within 30 s. And its complex [MQDA–Eu3+] was successfully used for the detection of TCs. Upon coordination of a carboxyl of MQDA with Eu3+ to form a [MQDA–Eu3+] complex, the carboxyl served as an antenna ligand for the effective detection of Eu3+ to intensify the emission intensity of MQDA via “antenna effect”, the process was the energy absorbed by TCs via UV excitation was effectively transferred to Eu3+. Fluorescence quenching of the [MQDA–Eu3+] complex was caused by the IFE in multicolor fluorescence systems. The limits of detection of [MQDA–Eu3+] for oxytetracycline, chlorotetracycline hydrochloride, and tetracycline were 0.80, 0.93, and 1.7 μM in DMSO/HEPES (7:3, v/v, pH = 7.0), respectively. [MQDA–Eu3+] demonstrated sensitive detection of TCs in environmental and food samples with satisfactory recoveries and exhibited excellent imaging capabilities for TCs in living cells and zebrafish with low cytotoxicity. The proposed approach demonstrated considerable potential for the quantitative detection of TCs.

Tuning lanthanide luminescence from bipyridine-bis(oxazoline/thiazoline) tetradentate ligands

Organic ligands play a pivotal role in lanthanide luminescence by acting as sensitizers for energy absorption and transfer, a phenomenon known as the fluorescence antenna effect. Herein, we introduce two tetradentate nitrogen ligands renowned for their efficient sensitization of lanthanide luminescence, with their luminous efficacy finely adjustable through subtle modifications to their structure. Through the synthesis of four Eu(III)/Tb(III) mononuclear complexes via the complexation of ligands 6,6′-bis(4,5-dihydrooxazol-2-yl)-2,2′-bipyridine (bpybox, L1) and 6,6′-bis(4,5-dihydrothiazol-2-yl)-2,2′-bipyridine (thio-bpybox, L2) with europium/terbium trifluorosulfonate, structural analysis reveals that the lanthanide ion coordinates with eight nitrogen atoms from two ligands and one oxygen atom from trifluorosulfonate. Among them, two Eu(III) complexes ([Eu(L1)2(SO3CF3)](SO3CF3)2EuL1 and [Eu(L2)2(SO3CF3)](SO3CF3)2EuL2) and one Tb(III) complex ([Tb(L1)2(SO3CF3)](SO3CF3)2 TbL1) exhibit luminosity, displaying characteristic lanthanide metal ion luminescence characterized by high fluorescence quantum yields and prolonged excited state lifetimes. In contrast, TbL2 ([Tb(L2)2(SO3CF3)](SO3CF3)2) is non-luminous, with the sole structural distinction being the substitution of oxygen atoms with sulfur atoms within the ligand. This minor alteration significantly impacts the triplet (3T) state energy level of the ligands, thereby influencing their sensitizing effect on Tb(III) luminescence. These findings underscore the remarkable efficiency of bpybox-type ligands as sensitizers for Ln(III) luminescence, with their structural versatility enabling effective modulation of luminous capacities and efficiency.

Dual-ligand Eu-MOF/CuS@Au Heterostructure Array-based ECL Sensor for MiRNA-128 Detection in Glioblastoma Tissues

In this work, the dual-ligand lanthanide metal-organic framework (MOF)-based electrochemiluminescence (ECL) sensor was constructed for the detection of miRNA-128 in glioblastoma (GBM) diagnosis. The luminescent Eu-MOF (EuBBN) was synthesized with terephthalic acid (BDC) and 2-amino terephthalic acid (BDC-NH2) as dual-ligand. Due to the antenna effect, EuBBN with conjugated-π structure exhibited strong luminescent signal and high quantum efficiency, which can be employed as ECL nanoprobe. Furthermore, the novel plasmonic CuS@Au heterostructure array has been prepared. The localized surface plasmon resonance coupling effect of the CuS@Au heterostructure array can amplify the ECL signal of EuBBN significantly. The EuBBN/CuS@Au heterostructure array-based sensing system has been prepared for the detection of miRNA-128 with a wide linear range from 1 fM to 1 nM and a detection limit of 0.24 fM. Finally, miRNA-128 in the clinic GBM tissue sample has been analysis for the distinguish of tumor grade successfully. The results demonstrated that the dual-ligand MOF/CuS@Au heterostructure array-based ECL sensor can provide important support for the development of GBM diagnosis.

Rapid and reliable ratiometric fluorescence detection of isoquercitrin based on a high-nuclearity Zn(II)-Nd(III) nanomolecular sensor

Rapid and quantitative detection of isoquercitrin (Isq) has been attracting much attention due to its outstanding pharmacological and physiological activities. Herein, an interesting 48-metal Zn(II)-Nd(III) nanocluster (1, molecular sizes 1.3 × 2.8 × 3.1 nm) with salen-type Schiff base ligand was constructed as molecular sensor for the luminescence detection of Isq. 1 exhibits visible ligand-centered emission and NIR luminescence of Nd(III), and shows ratiometric fluorescence response to Isq with high sensitivity even in the presence of other interferences. The fluorescence sensing behavior can be expressed by a second-order equation I1060nm/I480nm = A*[Isq]2 + B*[Isq] + C, which is used to quantitatively analyze the Isq concentrations in DMF and FCS. The LODs to Isq for the ligand-centered and lanthanide emissions of 1 in DMF are 0.21 μM and 0.11 nM, respectively. The quenching of the ligand-centered emission of 1 caused by Isq is attributed to the competitive absorption of light energy and “inner effect”, while, the luminescence enhancement is due to the “antenna effect”.

Binuclear TbⅢ complex used for the fluorescent detection of 2, 6-pyridindicarboxylic acid, an anthrax biomarker

Anthrax is a potentially highly lethal acute infectious disease caused by the zoonotic bacterium Bacillus anthracis, which poses a threat to human life and health. 2, 6-Pyridinedicarboxylic acid (DPA) is a significant component of bacterial spores as a typical anthrax biomarker. Therefore, it is imperative to develop a simple and efficient detection method for DPA. Here, we successfully synthesized a binuclear terbium complex with formulas [Tb2(DMOMP)2(CH3OH)2(H2O)4Cl2]·2Cl·2CH3OH, which is constructed by 2, 6-dimethoxy-4-methylphenol (DMOMP) and TbⅢ ion. Each TbⅢ ion center is encapsulated by seven O atoms and one Cl− anion. Based on this, the encapsulated coordination environment facilitated efficient ligand energy transfer via the “antenna effect”. Therefore, the complex exhibits interesting luminescence response characteristics, with fast and stable green fluorescence response to DPA, low detection limit Ksv = 1.08 × 10−5 M−1, and fluorescence lifetime τ = 754.93 μs. [Tb2(DMOMP)2(CH3OH)2(H2O)4Cl2]·2Cl·2CH3OH has excellent fluorescence properties and strong immunity to interference and is capable of sensitively detecting the B. anthracis biomarker DPA, allowing it to be potentially used as an effective fluorescent probe and providing a viable strategy for effective anthrax fever prevention.

Antenna Effect in Large Area Palladium-Coated Electrostatically Formed Silicon Nanowire for Ppb Level Hydrogen Sensing

Antenna Effect in Large Area Palladium-Coated Electrostatically Formed Silicon Nanowire for Ppb Level Hydrogen Sensing

Fabrication of diamond film under low methane concentration by hot filament chemical vapor deposition with magnetic field assistance

This study focused on improving diamond film growth through hot filament chemical vapor deposition (HFCVD) with an innovative method, magnetic field assistance. The effects on diamond films were thoroughly investigated using a combination of experiments and simulations. The results of scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD) all showed significant improvements in nucleation rates, film thickness, and grain size, particularly for grains with (111) orientation, when exposed to a 400 mT magnetic field during HFCVD compared to non-magnetic conditions. Magnetic field application in HFCVD was found to promote the formation of larger diamond grains and increase the film growth rate by nearly 45 %. Concurrent Finite Element Method simulations confirmed that the magnetic field improved reactive gas flow and temperature distribution across the substrate, which was consistent with experimental results. These findings suggest that magnetic field assistance in HFCVD may mitigate the limitations of bias assistance, such as the antenna effect, overheating, and stress imbalance. This approach is especially useful for substrates with complex geometries, such as the sharp edges of cutting tools, as it promotes even film growth.

Ratiometric fluorescence sensor based on deep learning for rapid and user-friendly detection of tetracycline antibiotics

The detection of tetracycline antibiotics (TCs) in food holds great significance in minimizing their absorption within the human body. Hence, this study aims to develop a rapid, convenient, real-time, and accurate detection method for detecting antibiotics in an authentic market setting. A colorimetric fluorescence sensor was devised for tetracycline detection utilizing PVA aerogels as the substrate. Its operating principle is based on the IFE effect and antenna effect. A detection device is designed to capture fluorescence images while deep learning was employed to aid in the detection process. The sensor exhibits high responsiveness with a mere 60-s requirement for detection and demonstrates substantial color changes(blue to red), achieving 99% accuracy within the range of 10–100 μM with the assistance of deep learning (Resnet18). Real sample simulation tests yielded recovery rates between 95% and 130%. Overall, the proposed strategy proved to be a simple, portable, reliable, and responsive solution for rapid real-time TCs detection in food samples.

CuS-CuO nanoparticles for antennas collect light through their conductivity by absorbing a single photon located at the wavelength of 254 nm

CuS-CuO nanoparticles were prepared by air annealing as-made CuS nanoparticles deposited using spray pyrolysis. The optical, structural, and morphological properties of samples were investigated by UV–VIS Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The XRD analysis of as-prepared sample include two phases CuS and Cu2S, while annealed films are a mixture of CuS and CuO phases. The dimensions of the CuS crystallites were estimated by Williamson's method on the diffraction peaks (81 nm) while the dimensions of the CuO ones were statistically evaluated via the SEM image (95 nm) and corroborated by Williamson's method on the diffraction peaks (98 nm). SEM study of annealed samples reveals that nanoparticles are monocrystalline. Optical analysis shows more than 80 % transmittance through sample thickness 164 nm in the infrared region and two energy bandgaps of 1.92 and 2.50 eV in the visible region associated with CuO and CuS, respectively. In addition, we observe after several optical excitations that only the UV wavelength of 254 nm gives a tangible electrical response. We understand from the literature that this is only possible through one interpretation of the antenna effect. Optical antennas aim to freely change light rays into local energy. In fact, our sample presents nanoparticles with sizes around 80 nm that show clear absorption through the development of their reproducible resistance that increases with polarization toward saturation after 5 V. Therefore, we propose using prepared nanoparticles in a light-harvesting antenna for artificial photodetector and other optoelectronic applications.

Nano antenna-assisted quantum dots emission into high-index planar waveguide

Integrated quantum photonic circuits require the efficient coupling of photon sources to photonic waveguides. Hybrid plasmonic/photonic platforms are a promising approach, taking advantage of both plasmon modal confinement for efficient coupling to a nearby emitter and photonic circuitry for optical data transfer and processing. In this work, we established directional quantum dot (QD) emission coupling to a planar TiO2 waveguide assisted by a Yagi-Uda antenna. Antenna on waveguide is first designed by scaling radio frequency dimensions to nano-optics, taking into account the hybrid plasmonic/photonic platform. Design is then optimized by full numerical simulations. We fabricate the antenna on a TiO2 planar waveguide and deposit a few QDs close to the Yagi-Uda antenna. The optical characterization shows clear directional coupling originating from antenna effect. We estimate the coupling efficiency and directivity of the light emitted into the waveguide.

Fast fluorescence sensing of aflatoxin B1 employing a europium metal–organic framework avoiding self-fluorescence interference of target

Aflatoxin B1 (AFB1) easily contaminates grain, oil, and their products, and is strongly carcinogenic. Therefore, rapid, efficient and sensitive detection of aflatoxin plays a key role in the food industry. Here, we prepared a lanthanide metal-organic framework termed Eu-TCPP, in which the ligand can effectively sensitize Eu3+ with excellent photoluminescence properties. It is worth mentioning that the fluorescence intensity of Eu-TCPP is at 617 nm, which can avoid the interferences of AFB1 self-fluorescence emitting in the range of 400 nm–500 nm. Eu-TCPP can efficiently detect AFB1 without using antibody or biomolecular modifications, exhibiting a rapid response of 60 seconds and a limit of detection (LOD) at 11.63 ppb. The Eu-TCPP sensor also has satisfactory performance for determining AFB1 sensitively in real oil samples. In addition, the mechanism of the excellent detection performance of Eu-TCPP has been investigated using density-functional theory (DFT) calculations combined with experimental analysis. The results show that the LUMO energy level of the ligand is higher than that of the aflatoxin, which causes the electrons transfer toward the targets, and results in the reduction of the fluorescence intensity. Therefore, our proposed Eu-MOF materials based on the "antenna effect" have great potential for the development of simple, fast, and sensitive small-molecule sensors, and offer a promising prospect in POCT applications.

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4′,4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the “antenna effect”. It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0–50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.