29 results about "Nanohole array" patented technology

The invention relates to the technical field of biosensors, and particularly discloses a preparation method of a multi-channel solid nanopore array. The method comprises the following steps: respectively constructing a group of parallel and independent micro-channels on the front and back surfaces of a chip prepared with a suspended dielectric film window array, enabling the micro-channels on the two surfaces to be orthogonally arranged in space, integrating an independent electrode in each micro-channel, and injecting electrolyte; the electrodes of the micro-channel on one side and the electrodes of the micro-channel on the other side are selectively connected through an external control circuit, namely controllable electric fields can be established on the two sides of the thin film window at the unique intersection point corresponding to the electrodes, so that addressing and selective dielectric breakdown of the window are achieved, all the windows on the whole chip are automatically and sequentially addressed, traversed and processed, and the yield of the chip is improved. And forming a nanopore array. By means of the method, a large number of nanopore arrays can be controllably manufactured on a single chip at a time, and nanopore array machining with high throughput, low cost and high consistency is achieved.

The invention relates to the technical field of surface plasma photonics and micro-nano optical sensing, in particular to a porous super-structure plasma sensor and a preparation method and application thereof.The porous super-structure plasma sensor comprises a substrate, and a first metal layer, a first silicon dioxide layer, a second metal layer and a second silicon dioxide layer are sequentially arranged on the substrate; a plurality of nanopore arrays are arranged on the porous superstructure plasma sensor; and the nanopore array penetrates through the first silicon dioxide layer, the second metal layer and the second silicon dioxide layer. Through the synergistic effect of a metal-medium-metal-medium (such as gold / silicon dioxide / gold / silicon dioxide) multi-layer structure and the periodic nanopore array, strong surface plasmon resonance is excited in a visible light-near infrared band, perfect combination of high absorptivity, high sensitivity and high FOM value is realized, and the sensor can be used for gas concentration change detection, and can be applied to detection of gas concentration changes. The problem that an existing plasmon sensor cannot meet the working requirement of the visible light-near infrared band is solved.

The application discloses a pretreatment cleaning agent processing control system and method, relates to the technical field of processing control, and injects a light-controlled origami probe solution into a nano-pore array of a piezoelectric ceramic chip, uses an AFM probe to apply an axial force to activate an origami structure, records a curve of force change with AFM probe displacement in real time, extracts folding displacement of a folding state area and complete unfolding displacement of a complete unfolding area, integrates and calculates the curve to obtain processing free energy, compares the processing free energy with a free energy range of high-quality cleaning agent finished products in a preset database, and if the processing free energy falls within the range, it is determined that current process parameters are in a reasonable interval, the parameters are maintained, and an efficiency label is marked as 1, and if the processing free energy exceeds the range, it is determined that the process is abnormal, an efficiency label is marked as 0, and dynamic adjustment is triggered. The control method not only improves the precision and efficiency of cleaning agent processing, but also reduces the rate of defective products and production loss, and provides key technical support for large-scale and stable production of high-quality cleaning agents.

The invention relates to a funnel diode realized based on a nanopore modified dielectric polymer molecule monolayer, and relates to the technical field of semiconductor devices. The preparation method of the funnel diode comprises the following steps: forming a three-layer PVP dielectric film through bi-crosslinking treatment, and constructing a nanopore array on the surface of the three-layer PVP dielectric film by using a soft nanoimprint technology to form a polymer nano dielectric layer; sequentially depositing an organic semiconductor layer and a top electrode to complete a diode main body structure; and finally, integrating a molecular memory monolayer formed by gold nanoclusters or copper stearate. The device is compact in structure, the unidirectional convergence of current carriers is realized by utilizing a funnel effect generated by the nanopores, and the device has the characteristics of high-voltage rectification ratio and ultralow working voltage under the coordination of a single molecular layer, and has nonvolatile storage and synaptic plasticity.

The invention discloses a reversible dynamic aperture solid nanopore array based on a temperature-sensitive phase change layer and a preparation method and application of the reversible dynamic aperture solid nanopore array, and belongs to the technical field of single molecule detection and nanostructure regulation, the array introduces the temperature-sensitive phase change layer into the inner wall of a solid nanopore, and when the local temperature crosses the phase transition point of the temperature-sensitive phase change layer, reversible volume change is generated; therefore, the effective aperture of the nanopore is continuously adjustable in a sub-nanometer scale range. An independent micro heating unit and an independent temperature sensing unit are integrated below each nanopore in the array, and single-pore-level accurate temperature control adjustment is achieved in a row-column addressing mode. In combination with ionic current monitoring and an external control module, the aperture can be set in real time according to the size requirements of different target molecules, and dynamic aperture regulation and control with a programmable structure, quick response and good repeatability are realized. The array structure provided by the invention is suitable for single molecule level detection of objects such as multiple types of small molecule pollutants, tumor-related biomarkers, biomacromolecules and the like, and has the advantages of high sensitivity, high flux and wide applicability.

The utility model provides a kind of refractive index sensing device based on titanium dioxide nanopore array, it is related to micro-nano photoelectronic technical field, the device includes titanium dioxide substrate, the titanium dioxide substrate surface is equipped with the nanopore array of square periodic arrangement;Gold film layer, the gold film layer covers in nanopore side wall and hole bottom surface;Silver film layer, the silver film layer covers in the upper surface of the titanium dioxide substrate, and the silver film layer with the gold film layer is connected at the orifice edge of nanopore;Silica protective layer, the silica protective layer covers in the exposed surface of the gold film layer, silver film layer, forms the package protection of metal layer.The utility model improves sensitivity and quality factor, and with low-cost material and local coating reduces cost and simplifies structure, also rely on protective layer to enhance stability, realize high performance and economy compatibility.

The application belongs to the technical field of molecular detection, and discloses a medicinal material identification system and method; the method comprises the following steps: emitting a topological protection acoustic wave to concentrate DNA of medicinal materials, marking the DNA with a CdTe quantum dot-nucleic acid probe, scraping the sample to extract DNA and performing PCR amplification, designing a logic gate staple chain to prepare a light-controlled origami probe, and injecting a PZT chip nano-pore array to be light-activated, and then, through AFM analysis of free energy, the medicinal materials are identified; the application constructs a complete technical chain from molecular recognition to reliable storage, and comprehensively solves multiple technical bottlenecks of traditional methods in medicinal material identification.

This invention relates to an antireflection structure, fabrication method, and application of inverted conical nanopores on the surface of SiC thin films, belonging to the field of surface engineering technology for photoelectric detectors. Addressing the problems of short optical path length and high interface reflection loss in existing SiC thin-film ultraviolet photodetectors based on heterogeneous substrates due to limited film thickness, a periodic array of inverted conical nanopores is constructed on the SiC thin film surface. The etching depth is controlled within the film thickness and does not penetrate the entire film, preserving a continuous electrical transmission channel. This structure creates a continuously gradient equivalent refractive index layer on the surface, reducing the surface reflectivity in the 200–400 nm wavelength range. The inverted conical morphology causes large-angle scattering of incident light, increasing the optical path length of ultraviolet light within the confined film and improving absorption. The array is fabricated using patterned masking technology combined with dry etching, suitable for SiC thin-film MSM or PIN detectors, with an average reflectivity of 7.58%, significantly improving the photoelectric conversion efficiency of the device.

The invention discloses a bionic anti-interference-precursor prediction collaborative high-speed vehicle anomaly detection system. The system comprises a composite circuit board, a multi-modal data processing module, a precursor prediction and diagnosis module, a closed-loop feedback optimization module and an emergency collaborative module. The composite circuit board is of a three-layer stacked structure. A bionic lotus root gradient honeycomb and a micro-channel cooling device are arranged on the bottom layer, and temperature self-adaptive control is achieved. The middle layer is integrated with a precursor characteristic acquisition link and an EMI filtering unit, so that high-precision data acquisition is guaranteed; the bionic cicada wing nanopore array and the spectrum analysis unit are arranged on the surface layer, and environmental protection and electromagnetic interference suppression are both considered. The multi-modal data processing module generates vehicle and hardware feature vectors; the precursor prediction module adopts an improved LSTM and outputs graded early warning and abnormal types; the closed-loop feedback module performs bidirectional optimization on hardware parameters and model parameters; and the emergency cooperation module broadcasts abnormal information through the Internet of Vehicles and triggers hierarchical response. According to the invention, the high-speed scene anomaly detection precision and early warning timeliness are improved, and the system stability is enhanced.

This invention discloses a metamaterial-based composite stealth film, its preparation method, and its applications, belonging to the field of multi-camouflage technology. The metamaterial-based composite stealth film disclosed in this invention includes an anodic aluminum oxide template and an amorphous alloy film deposited on its surface. The anodic aluminum oxide template has a nanopore array structure. In this invention, the anodic aluminum oxide template and the amorphous alloy film in the metamaterial-based composite stealth film exhibit a synergistic effect, modulating infrared radiation through the photonic bandgap effect, suppressing laser reflection through surface plasmon resonance, and generating visible light camouflage through structural color, thereby achieving multi-camouflage capabilities in visible light, laser, and infrared light.

A component (8) adapted to engage with a receiver (6) has an array of contact pads (16) to removeably connect with a corresponding array of connectors (18) on the receiver (6). Each contact pad (16) of the array is electrically connected to the electrode (26) of a corresponding recess or well (28) that is part of a sensor, wherein a membrane is formable across each recess. A conductive grid (102) is configured between the contact pads (16) of the array, to inhibit an electrostatic discharge (ESD) conducting across the recesses or wells and / or direct an ESD away from the recesses or wells.

The application relates to an inorganic nanoparticle array with super-narrow surface lattice resonance and a large-area preparation method thereof, which comprises the following steps: a centimeter-level silicon nanopillar stamp is used to mold a polydimethylsiloxane nanopore array template; the nanopore array template is dipped into a polymer organic solution, and then the nanopore array template is placed on a surface-hydroxylated silicon wafer to form close contact; after the solvent is completely volatilized, a polymer nanopillar array is obtained; metal precursors are adsorbed on the polymer surface through electrostatic action, and the metal ions are reduced by oxygen plasma and the polymer is etched, finally, through thermal annealing, the inorganic nanoparticle array with super-narrow surface lattice resonance is obtained. Compared with the prior art, the application provides a low-cost and high-efficiency universal platform for the preparation of the inorganic nanoparticle array, and makes the large-scale preparation of the next generation of nanophotonic and electronic devices possible.

The invention discloses a preparation method of a plasmon nanopore array, which comprises the following steps: immersing a substrate sheet in a positively charged silane coupling agent solution, and drying to obtain a first surface; forming a single-layer polymer microsphere colloid on the first surface through self-assembly, and forming to obtain a second surface; removing the silane coupling agent layer, which is not shielded by the microspheres, on the second surface to obtain a third surface; removing the microspheres on the third surface, and exposing the array region covered with the silane coupling agent layer to obtain a fourth surface; the fourth surface is immersed in a gold particle solution containing a protective agent, gold particles are electrostatically adsorbed in the array area, and a fifth surface is obtained; and performing high-temperature annealing on the fifth surface to obtain the plasmon nanopore array. The method provided by the invention is simple in preparation process and controllable in structure, and has wide application prospects in the aspects of life science, medical diagnosis and the like.

This invention discloses a titanium carbide film integrated gold-filled silicon aperture X-ray detector and its fabrication method, comprising: a silicon layer with a bottom contact electrode disposed below it and an insulating dielectric layer with perforated windows disposed above it; a nanopore array disposed on the inner surface of the silicon layer within the region corresponding to the perforated windows and connected to the silicon layer; gold nanopillar structures disposed at the bottom of the nanopores; a top electrode disposed above the insulating dielectric layer, the top electrode not covering the main detection area of ​​the perforated windows, and electrically connected to the detection area corresponding to the perforated windows through the titanium carbide nanofilm covering it; and a titanium carbide nanofilm disposed above the top electrode, the insulating dielectric layer, the gold nanopillar structures, and the nanopore array and in direct contact. This invention utilizes the built-in electric field of the titanium carbide nanofilm / silicon Schottky junction to promote the separation and collection of radiative carriers, achieving low-bias, high-sensitivity, and long-term stable direct X-ray detection.

The utility model relates to a kind of nanometer injection molding backboard, comprising: metal substrate, its surface is equipped with nano hole array;Plastic side wall, it is covered in the four peripheral edges of the metal substrate, the plastic side wall has the penetration portion extending to the surface of metal substrate, and the penetration portion is filled and anchored in nano hole and forms mechanical interlocking structure.The utility model has the beneficial effects of being capable of improving the connection strength, ensuring the stability of connection, and being capable of reducing cost.

The application discloses a manufacturing method of amorphous silicon film, comprising the following steps: growing a silicon dioxide film on an oriented grain silicon substrate; forming a nano-pore array layer with a preset pore diameter and a preset porosity on the surface of the silicon dioxide film; growing an amorphous silicon film on the nano-pore array layer; and performing annealing treatment on the amorphous silicon film. The technical scheme of the application can manufacture high-quality and uniform amorphous silicon film, and has the advantages of small manufacturing difficulty, simple process, low manufacturing cost and the like, and can meet the demand of large-scale production.

The invention discloses a mid-infrared topological polarization singular point laser and a preparation method thereof, and relates to the technical field of lasers. The method comprises the following steps: manufacturing a black phosphorus film sample by adopting a double-sided progressive stripping and single-sided thinning method; transferring the black phosphorus film sample to the metal substrate layer covered with the dielectric layer; determining an intermediate infrared wavelength corresponding to the target continuous domain constraint; based on the mid-infrared wavelength, the arrangement period and the aperture of the periodic circular hole array are designed; and based on the arrangement period and the aperture, etching the black phosphorus film sample on the metal substrate layer to obtain a black phosphorus gain layer with a two-dimensional periodic nanopore array structure on the metal substrate layer, thereby preparing the mid-infrared topological polarization singular-point laser, the black phosphorus gain layer with the two-dimensional periodic nanopore array structure is used for forming topological polarization singular points in a far field, so that the laser outputs mid-infrared laser with polarization vortex. The laser can overcome the defects that an existing laser is complex in structure, low in integration level, weak in polarization regulation and control capacity and the like.

The present disclosure relates to nanopore arrays. A readout device for a nanopore array is provided, as well as an analog detection circuit for the readout device. The detection circuit is connectable to a readout electrode of a nanopore array and, in a detection mode, applies a bias voltage to the readout electrode. When the bias voltage is applied, it extracts a baseline current from an input current flowing through the readout electrode and, if the input current changes compared to the baseline current by a predetermined threshold, outputs a digital signal indicating the occurrence of a current event. The readout device comprises the detection circuit and a logic device. The logic device determines, based on the digital signal, whether a translocation event has occurred in the nanopore. In this case, it provides an instruction signal to the detection circuit to switch from the detection mode to a readout mode.

A nanopore array device comprises a sensor, a detection circuit, one or more resistive heaters, and a temperature control circuit. The sensor comprises an array (9) of nanopore sensor elements (15A, 15B) configured to generate signals which are indicative of interactions between molecular entities and respective nanopores (29A, 29B) supported by each nanopore sensor element (15A, 15B). The detection circuit is configured to process the signals generated by the sensor, and to generate heat which heats the sensor. The one or more resistive heaters (57A, 57B) are configured to generate heat which heat the sensor. The temperature control circuit (49) is configured to control the one or more resistive heaters (57A, 57B) to maintain a temperature of the sensor above a predetermined minimum temperature.

The utility model relates to the technical field of lithium battery current collector materials, in particular to a composite copper foil with a nanopore structure, which comprises a base material layer, a nano functional layer arranged on the surface of the base material layer, and a metal layer arranged on one side of the nano functional layer away from the base material layer. The bonding force between the base material layer and the metal layer is enhanced through the nanometer functional layer, the nanometer functional layer serves as a transition layer, the difference of thermal expansion coefficients of the base material layer and the metal layer is effectively relieved, the layering phenomenon of the composite copper foil at the high temperature is avoided, the nanometer hole array in the nanometer functional layer provides a three-dimensional bonding interface, and the contact area of the metal layer and the base material layer is increased; the adhesive force of the copper layer is remarkably enhanced through the mechanical anchoring effect, meanwhile, the surface energy of the base material is improved through the nanometer functional layer, uniform nucleation of copper atoms on the surface of the base material is promoted, island-shaped growth is reduced, deposition of the copper layer is more uniform, the binding force is further improved, and the problems that traditional composite copper foil is poor in adhesive force, prone to layering at high temperature and the like are solved. The safety and the cycle life of the lithium battery are improved.

The invention discloses a method for processing a'golf tee 'nano-pillar array diamond reflector, which comprises the following steps of: S1, analyzing and acquiring optical parameters of polycrystalline diamond, and constructing a'golf tee' nano-pillar array three-dimensional model; s2, preparing a'golf tee 'nanopore array on the monocrystalline silicon substrate by adopting photoetching and anisotropic etching methods; s3, epitaxially growing polycrystalline diamond by adopting a microwave plasma chemical vapor deposition (MPCVD) method and taking the silicon substrate prepared in the step S2 as a growth substrate; s4, the amorphous polycrystalline diamond on the periphery is removed through a laser cutting method, and polishing of the upper surface of the epitaxial diamond is completed through mechanical polishing; and S5, wet etching is adopted to remove the monocrystalline silicon substrate, and finally, the nano-pillar array diamond reflecting mirror with the golf ball seat is obtained. The method has the advantages of being simple, low in equipment requirement, low in cost, capable of achieving wafer-level machining and the like, and is suitable for mass production of diamond reflectors.

The invention relates to a high-gain silicon-based narrow-band short-wave infrared photoelectric detector and a preparation method and application thereof. The high-gain silicon-based narrow-band short-wave infrared photoelectric detector comprises a substrate layer, a bonding glue layer, a first metal film layer, a silicon film layer and a second metal film layer which are sequentially stacked, the second metal film layer is provided with a nanopore array which is periodically arranged, and nanopores are through holes penetrating through the second metal film layer. According to the invention, the nanopore array is arranged in the second metal film layer, and the size and arrangement of the nanopores are regulated, so that effective detection of short-wave infrared light with energy lower than that of a silicon band gap and regulation of resonant wavelength can be realized. Besides, in cooperation with the avalanche multiplication effect induced by the photoelectric detector under the applied bias voltage, the responsivity can be improved by 6 orders of magnitude, and the responsivity at the wavelength of 1330 nm reaches 0.71 A / W, which is the highest value reported by the type of detectors at present. The photoelectric detector can be used for near-infrared imaging and solution recognition, the structure and the preparation process of the photoelectric detector are highly compatible with the CMOS technology, and the photoelectric detector has good integration potential and application prospects.

The invention relates to the technical field of biomolecule detection, in particular to a silicon-based nanopore array and a preparation method and application thereof.The preparation method of the silicon-based nanopore array comprises the following steps that S1, a first silicon nitride mask layer and a second silicon nitride mask layer are deposited on the front face and the back face of a p-type monocrystalline silicon wafer respectively; s2, performing anisotropic wet etching on the front surface of the p-type monocrystalline silicon wafer to obtain a plurality of first etching cavities; s3, performing wet etching on the reverse side of the p-type monocrystalline silicon wafer until the residual thickness of the p-type monocrystalline silicon wafer is 29-31 [mu] m; s4, etching the back surface of the p-type monocrystalline silicon wafer, and immediately stopping etching when monitoring that the current suddenly changes and reaches 20-40nA, so as to prepare an ordered nanopore array; s5, the ordered nanopore array is placed in a constant-temperature tube furnace for thermal oxidation for 2-8 h, the silicon-based nanopore array with the needed pore diameter of 9-18 nm is obtained, and the problems that an existing solid nanopore electric field is uneven in distribution, non-specific adsorption is achieved, and the pore diameter is difficult to control are solved.

The invention discloses a silicon-based reconfigurable optical logic gate structure based on a uniformly distributed phase change material, which is characterized in that a 6 [mu] m * 6 [mu] m waveguide region is designed on a silicon-based substrate, and the silicon-based reconfigurable optical logic gate structure comprises two bent input waveguides, a bias input waveguide and two output ports. The middle design area is etched into a 7 * 7 nanopore array, the pores are filled with phase change materials, and the materials can be switched between a crystalline state and an amorphous state so as to change the refractive index. The phase state of the phase change material is changed through an external electric heating control, so that the device is equivalent to different logic gate structures in different refractive index states, and the functions of an AND gate, an OR gate, an XOR gate and an XNOR gate can be reconfigured on the same chip. According to the invention, a binary particle swarm optimization algorithm is also adopted to optimize hole array arrangement so as to maximize the logic function output contrast. The device is excellent in output contrast ratio under the wavelength of 1550 nm, and expected logic function switching can be achieved. The reconfigurable optical logic gate is compact in structure, non-volatile and flexible in function, and a potential scheme is provided for integrated optical calculation.

The application discloses a kind of based on bismuth telluride super surface nano hole array subwavelength infrared antenna structure and preparation method thereof, it is related to super surface antenna design and infrared waveband application field.The structure with bismuth telluride as core material, by high-energy electron beam in transmission electron microscope 12×12 super surface nano hole array is prepared as subwavelength infrared antenna.The antenna is excited by the dipole source in array center, and is designed using full-wave finite-difference time-domain simulation optimization.Infrared waveband has 15dBi directivity coefficient, 14.5dBi gain and 93% radiation efficiency, and because of the high refractive index characteristics of bismuth telluride, subwavelength size design is realized.The application solves the problem of large ohmic loss and large size of traditional metal super surface antenna in infrared waveband, realizes miniaturization, high directivity and adjustable radiation characteristics, and has polarization adjustable potential.It can be widely applied in infrared communication, sensing and imaging and other fields.

The application discloses a kind of middle infrared topological polarization singularity laser and its preparation method, it is related to laser technical field.The method includes: using double-face progressive stripping, single-face thinning method, black phosphorus film sample is made;Black phosphorus film sample is transferred on the metal substrate layer covered with dielectric layer;Determine the corresponding middle infrared wavelength of target continuous domain bound pair;Based on middle infrared wavelength, the arrangement period and aperture of periodic circular hole array are designed;Based on arrangement period and aperture, black phosphorus film sample on the metal substrate layer is etched, and black phosphorus gain layer with two-dimensional periodic nanohole array structure on the metal substrate layer is obtained, to prepare middle infrared topological polarization singularity laser, wherein, black phosphorus gain layer with two-dimensional periodic nanohole array structure is used to form topological polarization singularity in far field, to make laser output with polarization vortex middle infrared laser.The application can overcome the defects such as complex structure, low integration, weak polarization control ability of existing laser.

The application provides a composite gas diffusion layer, belongs to the technical field of new energy and fuel cells, and is used for a fuel cell membrane electrode, comprising a porous substrate layer and a composite microporous layer which are arranged in layers, and the porous substrate layer serves as a support body; the composite microporous layer comprises a conductive support layer and a selective screening layer, the conductive support layer is arranged on the surface of the porous substrate layer and is formed of a conductive framework of carbon nanotube networks; the selective screening layer is located on the surface of the conductive support layer away from the porous substrate layer, is formed by paving two-dimensional sheet materials and is attached to the conductive support layer, the two-dimensional sheet materials are distributed with an array of nano-pores of the order of Angstrom, and the aperture of the nano-pores is 0.35-0.8 nm. The application further provides a plurality of preparation methods of the composite gas diffusion layer and a preparation method of the fuel cell membrane electrode. The application can solve the technical problems of poor barrier effect of the membrane electrode on fuel penetration and low proton conductivity in proton exchange membrane fuel cells and direct methanol fuel cells.

This invention provides a phage targeted screening chip and method based on nanopores and aptamers, belonging to the field of phage targeted screening technology. The screening chip includes a multi-layer structure, consisting of a pretreatment layer, a screening layer, an amplification layer, and a detection layer from top to bottom. A filter membrane is disposed in the middle of the pretreatment layer; a sedimentation tank, serving as a lysis cell, is disposed in the middle of the filter membrane; a nanopore array is disposed in the middle of the screening layer; a reaction tank is disposed in the middle of the amplification layer; and a detection point region composed of a microwell array is disposed in the middle of the detection layer, with quantum dot storage tanks at the four corners. This solution achieves one-stop fully automated operation, not only avoiding errors and cross-contamination caused by manual operation, but also shortening the screening process, which traditionally takes several days, to within hours, making it particularly suitable for rapid diagnostic scenarios.

The application discloses a preparation method of a nanopore sensor based on specific antibodies and application thereof, and relates to the field of heavy metal monitoring.The method comprises the following steps: based on an electron beam exposure micro-nano processing technology, Si3N4 nanopores are prepared on a Si3N4 thin film substrate to obtain a Si3N4 nanopore array; and surface functionalization is performed on the Si3N4 nanopore array to fix specific antibodies on the nanopore surface; wherein the specific antibodies can be combined with target heavy metals to produce electric signal characteristic changes under a bias voltage.Compared with the prior art, the nanopore sensor prepared by the application has low cost and shows high selectivity and high sensitivity.