CN2504633Y - Molecular sieve modified resonance micro-beam chemical biosensor - Google Patents

Abstract

The utility model which relates to a resonant microcantilever chemicobiological sensor modified by the molecular sieve comprises a piezoelectric resonant socle beam and a high selectivity molecular sieve film, and wherein, the micro cantilever comprises three layers of electrodes: an upper electrode, a middle electrode and a lower electrode, and two layers of piezoelectricity layers which separate the three layers of electrodes. The upper layer and the lower layer are insulating, and the molecular sieve film layer is arranged on the top surface of the micro cantilever. The utility model has the advantages of high selectivity and sensitivity, good repeatability, being suitable for large scale production and reducing production cost.

Description

The resonance of the zeolite modified beam chemical biosensor that declines

Technical field

The utility model belongs to sensor technical field, is specifically related to a kind of resonance with zeolite modified beam chemical biosensor that declines.

Technical background

Little beam is used as the sensor that detects little power the earliest, as is used for acceleration transducer and atomic force microscope (AFM).In recent years, its measuring object is increasing, and as temperature, heat energy, magnetic field, quality etc., range of application also constantly enlarges, and identifies as chemical analysis, biological test, medicine screening, environment control, smell (as the essence drinks) etc.Resonance declines beam because high sensitivity is arranged, thereby has received increasing concern, and research concentrates on the contactless of high-resolution imaging and pats on formula scanning force microscopy (SFM), micromechanics electronic filter and the gas sensor.(referring to [1] H.P.Lang, et al, Analytica Chimica Acta 393 (1999) 59-65; [2] M.Maute, et al, MicroelectronicEngineering 46 (1999), 439-442; [3] M.D.Antonik, et al, IEEE Enginering inMedicine and Biology; [4] S.C.Mantell, et al, private contact; [5] A.Boisen, et al, Ultramicroscopy 82 (2000) 11-16.)

In chemical biosensor, spectral analysis can obtain the abundantest information, but it detects also complexity the most.The senser element that has occurred some cheap and simple recently, but perplexed by the selectivity difference mostly.Being usually used in strengthening optionally, material has polymeric membrane, metal oxide film and porosint etc.The hole material molecule sieve membrane of receiving has great significance to strengthening the sensor selectivity.It has duct size and the shape that can accurately control, and can modify the duct, and the screening of different molecular is had uniqueness, simultaneously it also have surface area-absorption mass ratio greatly, the advantages such as performance of mating very much with silica-base material are arranged.So far, have the report more than the molecular sieve of 150 kinds of different structures, this provides wide prospect for its application as sensitive material.(referring to [6] G-Zh, Yan, et al, ICSICT-2001:773-776; [7] O.Hugon, et al, Sensors and Actuators B 67 (2000) 235-243.)

The H.P.LANG group of Zurich, Switzerland IBM research department once carried out the Primary Study ([8] L.Scandella, et al, Microporous and Mesoporous Materials 21 (1998) 401-409) of little beam and molecular sieve combination.They place entire device on the exciting device at the molecular sieve of the little beam free end of monolayer silicon head with a sintering of epoxy resin adhesion again, adopt photoelectric method measuring vibrations frequency, and water vapour has been carried out detection test.But this method but can't drop into the practical application of sensor.Because 1) bonding molecule grate size on the beam of micro-meter scale, operating procedure and bonding consistance are poor, and manually-operated is repeatable poor; 2) add exciting device and photoelectric measuring device, it is integrated very difficult with microminaturization that sensor is realized; Simultaneously, when adopting laser interferometer to carry out photoelectric measurement, light must focus on little beam free end head, aims at the difficulty height, and the alignment point position consistency is poor.

Summary of the invention

The purpose of this utility model be to propose a kind of have from the exciting self check survey performance, resonance highly sensitive, that process consistency the is good beam chemical biosensor that declines.

The resonance of the utility model design beam chemical biosensor that declines is made up of multilayer film, and specifically be divided into two parts: high sensitivity is from the molecular screen membrane of exciting self-monitoring piezoelectric type resonance micro-cantilever and high selectivity.Its structure as shown in Figure 1.Wherein, piezoelectric type resonance micro-cantilever is made of upper, middle and lower-ranking electrode 4 and 2 layers of piezoelectric layer 3 space, and it has insulation course 2 respectively in both sides up and down; High selectivity molecular sieve rete 1 is located at the micro-cantilever upper surface.The substrate of sensor is a silicon chip.

Two-layer piezoelectric layer in this sensor is finished resonance, is realized the self-driven of sensor function and detection certainly.Its principle of work is as follows:

Piezoelectric has positive piezoelectricity and the contrary double effect of piezoelectricity, that is to say, under the certain voltage effect, the certain strain of the piezoelectric corresponding generation of meeting has a certain amount of voltage output and be added in deformation certain on the piezoelectric.Present technique is manufactured with two-layer piezoelectric layer on micro cantilever structure, wherein one deck promptly adds a certain amount of alternating voltage by electrode as the driving source of resonance on one deck piezoelectric layer, makes whole beam produce dynamic strain, with the frequency vibration of this alternating voltage; One deck is as the detection resources of resonance in addition.

The resonant frequency f of micro-cantilever system _iCan be expressed as simply: $f_i=\frac{{\mathrm{\λ}}_1^2}{2\mathrm{\π}{l}^2}\sqrt{\frac{\mathrm{EI}}{m}}------\left(1\right)$ Wherein, E, I are the Young modulus and the cross sectional moment of inertia of system, λ _iBe only relevant with boundary condition constant, l, m are respectively the length of beam and the quality of unit length.When the frequency of driving voltage reached the resonant frequency of system, peak value appearred in the amplitude of system.

On the micro-cantilever another layer piezoelectric layer can produce corresponding alternating voltage under the effect of above-mentioned dynamic strain, the frequency of measuring this alternating voltage can detect the resonant frequency of micro-cantilever system.

Can see that by formula (1) when the quality of micro-cantilever system changed Δ m, the resonant frequency of system also can correspondingly change, promptly $\frac{\mathrm{\Δ}{f}_i}{f_i}=\sqrt{\frac{1}{\mathrm{\Δm}/m+1}}-1--------\left(2\right)$ So the variation of the resonant frequency by measuring the micro-cantilever system can obtain the change amount of mass of system.

The utility model adopts the responsive source of the molecular screen membrane of high selectivity as sensor, and is significant.As chemical biosensor, selectivity and sensitivity have status of equal importance.Utilize the poriness of molecular sieve, by molecular sieve preparation and its structure of accuracy controlling, can be at the diameter and the chemical group characteristic of gas with various molecule, aperture and aperture inwall to molecular sieve carry out specific modification, realize to adsorb on this molecular screen membrane this specific molecule, thereby realize high selectivity; Simultaneously, because the effective surface area of molecular sieve---the absorption mass ratio is very big, through after the specific chemical modification, can improve the effective mass of absorption specific gas, can realize high sensitivity; And, molecular sieve has stable chemical characteristic, and therefore the responsive source of making sensor with molecular sieve can take multiple measurements, stable simultaneously chemical characteristic can guarantee to carry out various chemical modifications on molecular sieve, and then realizes the measurement to the number of chemical biomolecule.

Can adopt common gel-colloidal sol technology at micro-cantilever surface preparation molecular screen membrane.It had both utilized the above-mentioned characteristic of molecular sieve, had utilized the integrated circuit and the MEMS technology of preparing of standard again, had realized the consistance and the repeatability of molecular screen membrane manufacture craft.The combination of the two makes this chemical biosensor become a kind of practical technique.

Before and after the surface molecular sieve membrane absorption specific molecular or be modified on the film specific molecular with other measuring object effect (as the effect of antibody antigen etc.) before and after, the resonant frequency of micro-cantilever system changes, and can measure the molecular mass that is adsorbed or the effect situation between specific molecular and the measuring object.

The chemical biosensor of the utility model design has following characteristics:

1, selectivity is strong, and is highly sensitive.The specific modification of the aperture of molecular screen membrane and aperture inner membrance, the absorption mass ratio is big.

2, repeatable height, microminaturization, can be mass-produced, cheap.Adopt integrated circuit and MEMS technology of preparing, can guarantee large-scale production, the process repeatability height can be made up to a hundred devices on the every silicon chip simultaneously, because the development of various functional integrated circuits can make the total system microminiaturization, reduces cost.

3, many indexs property.Can utilize integrated circuit technique to make sensor array, on different micro-cantilevers, modify different molecular sieve structures,, realize that multiple (individual) index detects simultaneously different chemical biomolecule sensitivity.

4, non-marking.Without any need for sign material (as fluorescer etc.), directly detection is finished in the absorption of specific molecular and the change of frequency by molecular sieve.

Description of drawings

Fig. 1 is this sensor construction cut-away view.

Fig. 2 is coated with the response of the sensor of fluorine Lyons molecular sieve layer to fluorine Lyons gas of variable concentrations.

Fig. 3 is the selectivity experimental result of molecular sieve.Wherein, (a) be coated with the response of the dedicated molecular sieve used micro-cantilever in fluorine Lyons: ■ fluorine Lyons ◆ ethanol; (b) no molecular sieve micro-cantilever is to the response of gas:  fluorine Lyons ● ethanol.

Number in the figure: 1 is molecular screen membrane, and 2 is insulation course, and 3 is piezoelectric layer, and 4 is electrode layer.

Embodiment

Further describe the utility model below by embodiment.

Embodiment, micro-cantilever are of a size of 970 μ m * 300 μ m * 3 μ m.Its surface is for to have optionally MFI molecular screen membrane of uniqueness to fluorine Lyons molecule.

The manufacture craft flow process of sensor is: deposit Si on the silicon chip ₃N ₄/ SiO ₂Behind the layer, sputtered with Ti/Pt bottom electrode, use gel---sol gel process forms the piezoelectric layer PZT of lower floor, produces middle electrode, upper strata piezoelectric layer PZT and top electrode with identical technology, has generated SiO after the passivation ₂The surface forms micro-cantilever by back-etching.After the micro-cantilever surface is cleaned with AG acetone, at air drying, again will be only the MFI molecular sieve liquid of fluorine Lyons molecule sensitivity be carried out double dilution, obtain being about the molecular sieve suspending liquid of 0.002% (w/V), take out 0.2 μ l and be spin-coated on the micro-cantilever surface, through 10 minutes 100 ℃ bake, promptly finished the making of this sensor.

The micro-cantilever that is coated with the dedicated molecular sieve used layer in fluorine Lyons is seen shown in Figure 2 to the response of fluorine Lyons gas of variable concentrations.Frequency change has shown that along with the increase of gas concentration is exponential damping molecular sieve finally trends towards saturated absorption.

The selectivity experimental result of molecular sieve is seen shown in Figure 3.The micro-cantilever that is coated with the dedicated molecular sieve used layer in fluorine Lyons has shown the sensitivity to fluorine Lyons, and ethanol is not had response.The micro-cantilever that does not have any molecular sieve coating does not then all have significant response to fluorine Lyons and ethanol.In addition, experiment also shows the good reproducibility of this kind micro-cantilever, return-to-zero-time short (＜20 seconds).

Claims (3)

1, a kind of resonance of zeolite modified beam chemical biosensor that declines, form by multilayer film, specifically be divided into two parts: high sensitivity is from the molecular screen membrane of exciting self-monitoring piezoelectric type resonance micro-cantilever and high selectivity, it is characterized in that micro-cantilever is made of the 3 layers of electrode in upper, middle and lower (4) and 2 layers of piezoelectric layer (3) space, its upper and lower both sides have insulation course (2) respectively; High selectivity molecular sieve rete is arranged at the micro-cantilever upper surface.

2, sensor according to claim 1 is characterized in that diameter and chemical group characteristic at the gas with various molecule, and the aperture and the aperture inwall of molecular sieve carried out specific modification.

3, sensor according to claim 1 is characterized in that molecular screen membrane is the MFI molecular screen membrane.

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