Portable potentiostat application platform based on vitamin B detection
Technical field
The invention belongs to technical field of electrochemical detection, relate to a kind of based on vitamin B detection portable
Potentiostat application platform, it has merged electrochemical measuring technique based on three-electrode system and embedded system
System portable design method, for easily and fast, accurately in detection food, trace element (particularly ties up life
Element B) situation of content, and strong from design function, can be with other detecting system use in conjunction.
Background technology
Vitamin B (VB) is biological oxidation coenzyme important in cell, is that body maintains it normally to give birth to
A class nutrient necessary to living.The interpolation of food vitamins B, especially infant and breast milk are eaten
In product, it is necessary to control its addition by detection is strict, so finding a kind of simple, efficiently, quickly
Detection method is the most necessary.The analysis method of vitamin B mainly has fluorimetry, high performance liquid chromatography
Analytic process, ultraviolet spectrophotometry and electrochemical methods etc..And electrochemical methods is according to electrochemistry
Principle and material electrochemical properties in the solution and change thereof and the alanysis method set up, logical
Often take fixed potential under suitable current potential polarize or carry out electric potential scanning in relative broad range, there is behaviour
Work is simple, analysis speed is fast, accuracy advantages of higher, can realize analyzing continuously and field assay,
More and more applied.
At aspects such as material qualitative and quantitative analysis, Conventional electrochemical test, electrochemical reaction mechanism researchs,
Three electrode test systems suffer from extensively applying.But because it is expensive, volume big, and to coordinate
Upper computer software just can use, and makes it be restricted in terms of popularization and application, it more difficult to be applied to just
Take in formula detection equipment.Potentiostat is that various three electric pole types (include working electrode, auxiliary electrode and ginseng
Than electrode) interface of electrochemical sensor, mainly external drive signal is close to and puts on sensing exactly
On device, drive sample solution generation electrochemical reaction, and the response signal produced is done corresponding pretreatment
(signal is changed, amplifies, is filtered).The most backward due to semiconductor integration technology in early days, potentiostat master
To be made up of substantial amounts of discrete component, to there is the deficiencies such as bulky, structure is complicated, permanent electromotive force control difference,
Limit its range of application.
At present, the domestic potentiostat for laboratory electrochemical property test is due to its volume relatively greatly, stupid
Heavy and the most portable, be not suitable for the application of Practical Project scene.And the potentiostat of existing practical engineering application
Certainty of measurement is low, controls error relatively big, operation inconvenience, and intelligence degree is relatively low, it is impossible to meet on-the-spot electricity
Test chemical demand.Further, mcg vitamin detection technique in existing food, there is detection method multiple
Miscellaneous, the detection time is longer, testing cost is higher, be difficult to the shortcomings such as popularization, and detection device application is single
One, it is impossible to meet the actual demands such as food safety.Examine therefore, it is necessary to design is a kind of based on vitamin B
The portable potentiostat application platform surveyed, the most quickly detection of mcg vitamin B in food,
And expansible testing impedance platform carries out use in conjunction.
Summary of the invention
It is an object of the invention to for the deficiencies in the prior art, it is provided that a kind of based on vitamin B detect just
Taking formula potentiostat application platform, it can be used for the detection of mcg vitamin B in food, can be to every ginseng
Number carries out long-distance monitor and control and sends detection signal to remote server, and the later stage can be with electrochemistry
The Platform Alliance application such as impedance test system, its power supply adaptor is detachable with apparatus main body, external three electricity
Pole detection platform, can be connected with host computer, outward appearance hommization, portable design, have that volume is little, take
Band is convenient, detection quick and precisely, the feature such as simple to operate, use in conjunction.
For achieving the above object, the technical solution adopted in the present invention is:
The present invention is by housing unit, RS485 transport module, external equipment connecting line, and is arranged on shell
Power module in body assembly, micro controller module, D/A modular converter, amplifier detection module, A/D
Modular converter, relay group module, button display module and GPRS wireless communication module composition.Described
Power module connect micro controller module power input;D/A modular converter is by micro controller module
Digital quantity be converted into analog quantity and pass to amplifier detection module;A/D modular converter is by amplifier detection module
Sampled data be converted into digital quantity by analog quantity and pass to micro controller module and process;Microcontroller mould
In block, the conversion of pc port low and high level controls relay group module adhesive, thus controls amplifier detection
The connection status of working electrode in module;The parameter of setting is sent to microcontroller mould by button display module
Block carries out processing and the signal and the data that receive from micro controller module being shown;RS485 transmits mould
Block is connected with micro controller module, and the signal detected is passed to GPRS wireless communication module.
Described housing unit includes that shell, display screen, front vent, electromotion pilot lamp, function are selected
Select button, upper select button, printing-type electrode detection chip draw-in groove, USB interface, external application connect
Mouth, on and off switch, power interface, back side vent, signal translation interface and three electrode interfaces.
Described display screen, front vent, electromotion pilot lamp, function selecting button and select up and down to press
Button is arranged at outer casing top surface;Display screen place plane becomes 135 ° with function selecting button place plane;
Display screen connects internal key display module and is transmitted controlling by micro controller module, can show setting
Magnitude of voltage, current value and the detection time with detection;Front vent is made up of wire gauze;Energising instruction
Lamp is connected with power module, lights during energising;Function selecting button connects button display module, and will
The information set is transferred to micro controller module and is controlled, and including voltage, electric current, sweeps speed and sensitivity
Four arrange button;Upper select button is connected with button display module, adjusts function selecting knob
Voltage, electric current, sweep the ascending, descending of speed or sensitivity number.
Outside described printing-type electrode detection chip draw-in groove, USB interface and external application interface is arranged at
Shell-side face;USB interface and external application interface are all connected with micro controller module;Printing-type electrode detection core
Sheet draw-in groove is provided with two and assigns groove for assigning printing-type electrode detection chip;Printing-type electrode detection chip
Draw-in groove connects amplifier detection module.
Described on and off switch, power interface, back side vent, signal translation interface and three electrode interfaces
It is arranged at after shell;Power interface connects power module, and through power supply adaptor input direct voltage;
On and off switch connects power interface and power module, controls electric power starting and closedown;Back side vent is by ferrum
Silk screen forms;Signal translation interface connects RS485 transport module;Three electrode interfaces and amplifier detection module
It is connected.
Described power supply adaptor, USB connecting line, RS485 patchcord, three electrode connecting lines and external
Application connecting line constitutes external equipment connecting line.
Described micro controller module uses ATmega16 chip, by I/O mouth and relay group module
Connect, be connected with D/A modular converter and A/D modular converter by SPI communication interface.
Described D/A modular converter uses DAC8831 chip.
Described A/D modular converter uses AD7705 chip.
Described amplifier detection module includes voltage follower, feedback circuit and current follower, voltage with
Integrated operational amplifier is all comprised with device, feedback circuit and current follower;Described integrated operational amplifier
Model be OPA211;The integrated operational amplifier of voltage follower, feedback circuit and current follower divides
The electric current that three electrode interfaces transmit is not converted into voltage detection signal, and each voltage detection signal is sent
Enter D/A modular converter.
Described relay group module uses G6H-2-5VDC relay.
The present invention is the most advantageously:
1, the present invention is suitable for Electrochemical Detection, and constant potential error control, within mV level, detects electric current
Lower limit reaches 10-6A, uses three electrode sensings, sample is carried out stable signal detection, has sensitivity
The advantages such as height, system stability, compact overall structure;
2, present invention reduces the sample detection time, mcg vitamin B in food can be carried out easily
Detection, efficiently quicker than other detection methods, and sampling is repeated several times so that accuracy of detection, detection
Comprehensive have been improved, reduce testing cost, it is possible to fully meet Site Detection demand;
3, by GPRS wireless communication module, it is achieved between intelligent controlling device and remote monitoring platform
Communication, improves the operational efficiency of whole system, also saves manpower and materials.The present invention later stage can be in conjunction with
Other platforms carry out use in conjunction, add expansion, such as with impedance test system use in conjunction, right
The real-time simultaneous detection of biomembrane growth attaching situation under different vitamine concentrations;GPRS radio communication
Module realizes remotely controlling and the remote transmission of data of system, carries out detecting control to detection signal, will
The live signal detected is sent to remote server.Use transparent host-host protocol, compatible MODBUS
Host-host protocol, data transmit simpler convenience.
4, relay group module uses G6H-2-5VDC relay, and this model relay size is less, merit
Consuming relatively low, highly sensitive, electromagnetic interference is low, can be with high-density installation.
5, RS485 transmission is to use differential level to send signal, and jamproof ability is strong, signal transmission away from
Away from from.Present invention can apply to engineering site, working environment noise is big, if requiring, transmission range is farther out.
6, the nA level electric current that three electrode sensors are inputted by the integrated operational amplifier of amplifier detection module turns
Turn to voltage detection signal, send into D/A modular converter, utilize its high input impedance, high open loop times magnification
Number, the feature of low maladjustment voltage, effectively control the error of potentiostat.
7, the present invention meets current food safety detection trend, has that volume is little, is easy to carry, merit
The features such as energy is prominent, system working stability, intelligence degree are high, man machine interface is good, have wide
Application prospect and practical value, very easy to use.
Accompanying drawing explanation
Fig. 1 is the theory diagram of the present invention;
Fig. 2 is the axonometric chart of middle shell assembly of the present invention;
Fig. 3 is the schematic rear view of middle shell assembly of the present invention;
Fig. 4 is triple electrode circuit Simplified equivalent model figure;
Fig. 5 is that the present invention carries out output voltage test experiments data result to triple electrode circuit equivalent model
Figure;
Fig. 6 is the cyclic voltammetry curve figure that the present invention records on bare electrode and modified electrode;
Fig. 7 is the present invention and impedance test system use in conjunction schematic diagram.
Detailed description of the invention
Below in conjunction with detailed description of the invention, the invention will be further described, and protection scope of the present invention is not
It is confined to embodiment, the equivalent of every any this area implemented according to present disclosure or principle
Replace, belong to protection scope of the present invention.
As it is shown in figure 1, portable potentiostat based on vitamin B detection, by housing unit, RS485
Transport module 9, external equipment connecting line, and be arranged in housing unit power module 1, micro-control
Device module 2 processed, D/A modular converter 3, amplifier detection module 4, A/D modular converter 5, relay group
Module 6, button display module 7 and GPRS wireless communication module 10 form.Power module 1 connects micro-
The power input of controller module 2;The digital quantity of micro controller module 2 is turned by D/A modular converter 3
Change analog quantity into and pass to amplifier detection module 4;A/D modular converter 5 is by adopting in amplifier detection module 4
Sample data are converted into digital quantity by analog quantity and pass to micro controller module 2 and process;Micro controller module
In 2, the conversion of pc port low and high level controls relay group module 6 adhesive, thus controls amplifier detection
The connection status of working electrode in module 4;The parameter of setting is sent to microcontroller by button display module 7
Device module 2 carries out processing and the signal and the data that receive from micro controller module 2 being shown;
RS485 transport module 9 is connected with micro controller module 2, and the signal detected is transferred to host computer 8
Carry out feedback control, and the signal detected is sent to far in real time by GPRS wireless communication module 10
Journey server 11.
As shown in Figures 2 and 3, housing unit include shell 12, display screen 13, front vent 14,
Electromotion pilot lamp 15, function selecting button 16, upper select button 17, printing-type electrode detection chip
Draw-in groove 18, usb 19, external application interface 20, on and off switch 21, power interface 22, the back side
Vent 23, signal translation interface 24 and three electrode interfaces 25.
Display screen 13, front vent 14, electromotion pilot lamp 15, function selecting button 16 and select up and down
Select button 17 and be arranged at shell 12 end face;Display screen 13 place plane and function selecting button 16 institute
135 ° are become in plane;Display screen 13 connects internal key display module 7 and is entered by micro controller module 2
Row transmission controls, and can show and arrange and the magnitude of voltage of detection, current value and detection time;Front vent
14 are made up of wire gauze, increase the circulation of housing inner air and outer air;Electromotion pilot lamp 15 and power module 1 phase
Connect, during energising, light green;Function selecting button 16 connects button display module 7, and by setting
Information is transferred to micro controller module 2 and is controlled, and including voltage, electric current, sweeps speed and sensitivity four
Button is set;Upper select button 17 is connected with button display module 7, adjusts function selecting knob
The voltage of 16, electric current, sweep the ascending, descending of speed or sensitivity number.
Printing-type electrode detection chip draw-in groove 18, usb 19 and external application interface 20 are arranged at
Shell 12 side;Usb 19 and external application interface 20 are all connected with micro controller module 2;Printing
Formula electrode detection chip draw-in groove 18 is provided with two and assigns groove for assigning printing-type electrode detection chip, no
Indentation housing during use;Printing-type electrode detection chip draw-in groove 18 connects amplifier detection module 4;USB connects
Mouth 19 can carry out signal transmission by USB connecting line and miscellaneous equipment;External application interface 20 is by outward
Scooping out and can carry out use in conjunction by external miscellaneous equipment with connecting line, being applied to each needs this portable permanent electricity
The occasion of position instrument control, as carried out joint-detection with impedance test system.
On and off switch 21, power interface 22, back side vent 23, signal translation interface 24 and three electrodes
Interface 25 is arranged at after shell 12;Power interface 22 connects power module 1, and through power adaptation
Device input direct voltage;On and off switch 21 connects power interface 22 and power module 1, controls power supply and opens
Open and close;Back side vent 23 is made up of wire gauze, increases the circulation of housing inner air and outer air, strengthens and dissipate
Heat;Signal translation interface 24 connects RS485 transport module 9, and by RS485 patchcord, signal is remote
Distance Transmission communicates to host computer 8;Three electrode interfaces 25 are connected with amplifier detection module 4,
And be connected by three electrode connecting lines and three electrode detection platforms.
Power supply adaptor, USB connecting line, RS485 patchcord, three electrode connecting lines and external application are even
Wiring constitutes external equipment connecting line.
The present invention carries out early stage performance test test and later stage application experiment to this potentiostat application platform
Test.
1, early stage electrochemical property test
1.1 are equivalent to resistance, electric capacity string according to circuit equivalent principle in electrolyzer three interelectrode relations
The impedance model of parallel form, as shown in Figure 4, electric double layer capacitance, electrode, solution and electrode reaction
Caused impedance is analyzed, it is believed that resistance RSIt is equivalent to working electrode and to solution between electrode
Resistance, RFW、CFWThe equivalent electric double layer impedance that to be working electrode produce on the contact surface with electrolyte.Use
This triple electrode circuit equivalent model carries out performance test, sets R in experimentSFor 1K Ω, CFWIt is 50 μ F,
RFWResistance value be continually changing (1,10,30,5,100,200K Ω), concurrently set input not
Same magnitude of voltage (magnitude of voltage of WE Yu RE go-and-retum) be respectively 0.100,0.500,1.000,2.000,
3.300V, tests the output voltage situation of this potentiostat application platform.Test data of experiment result such as table
Shown in 1.
Table 1 uses triple electrode circuit equivalent model to carry out output voltage test tables of data
Fig. 5 for carrying out output voltage test experiments data result figure to triple electrode circuit equivalent model.Pass through
Table 1 and Fig. 5 can be seen that change RFWResistance value time, output voltage kept stable, RFWResistance
The change of value is on output voltage almost without impact, and output voltage follows setting voltage change.
1.2 use triple electrode circuit equivalent model to test the output electric current feelings of this potentiostat application platform
Condition.First set RFWResistance value when being 1K Ω, change CFWCapacitance be respectively 50 μ F, 100 μ F,
150 μ F, the different magnitudes of voltage (magnitude of voltage of WE Yu RE go-and-retum) of set input respectively 0.1,
0.5,1.0,2.0,3.3V, measure the output current value of this potentiostat application platform;Reset CFW
Capacitance when being 100 μ F, change RFWResistance value be respectively 0.5K Ω, 1K Ω, 1.5K Ω,
The different magnitudes of voltage (magnitude of voltage of WE Yu RE go-and-retum) of same set input respectively 0.1,0.5,
1.0,2.0,3.3V, measure the output current value of this potentiostat application platform, test data of experiment is tied
Fruit is as shown in table 2.
Table 2 uses triple electrode circuit equivalent model to carry out exporting testing current tables of data
Be can be seen that by table 2 and work as RFWResistance value when fixing, the change of electric capacity is to output current value slightly
Impact, but impact is little, because the electrolyzer of capacitive can bring faint noise, table 2 to show to measuring
Outputting current steadily is within the specific limits;When capacitance is fixed, output electric current is along with the increase of resistance value
And linearly reduce, coincidence theory value, its measurement data stability and precision meet requirement of experiment.
2, later stage application experiment test
2.1 in order to verify and highlight the present invention performance and application whether meet the requirements, use cyclic voltammetric
Method, at the potassium ferricyanide/potassium ferrocyanide solution ([Fe (CN) of variable concentrations6]3-/4-In), carry out this
The bright measurement of comparison with CHI660C work station is tested: 1) configured [Fe (CN) of 100mM/L6]3-/4-Molten
Liquid, being diluted to concentration respectively by PBS solution is 50mM/L, 25mM/L, 12.5mM/L, 6.75mM/L
Buffer, 2) be circulated voltammetry test, initial potential-0.2V, settling time 2S, electrode is swept
Speed respectively 10mV/S, 25mV/S, 50mV/S, 100mV/S, 3) record more redox two
Individual peak point current ip1 and ip2.Experimental data is as shown in table 3, wherein, in ip1 Yu ip2 numerical value
Being positioned at the measured value that value above is CHI660C work station, value below is the measured value of the present invention.
Table 3 uses CHI660C and the present invention to record [Fe (CN) 6]3-/4-Buffer is at variable concentrations and the output current value under sweeping speed
By table 3 it can be seen that its current value of buffer of same concentrations linearly increases with the increase sweeping speed
Add, identical sweep its current value under speed and linearly reduce with the minimizing of buffer concentration, all become substantially linear to close
System, it tests data fit notional result.By drawing with commercial CHI660C contrast, this
Bright measurement stability reaches requirement, can be accurate to 10-6A, meets the application requirement of reality.
2.2 present invention are to mcg vitamin B in food2Content carries out test experience, and using pH is 4.0
The Potassium Hydrogen Phthalate buffer of 0.1mol/L as electrolyte (vitamin B2Concentration be 2 ×
10-5Mol/L), sweep speed is 0.1V/s, tests, record and follow on bare electrode and modified electrode
Ring volt-ampere curve figure is as shown in Figure 6.As can be seen from Figure 6, the curve that bare electrode records is almost without peak
Value change, and steadily without any response, on modified electrode, a pair sharp-pointed oxidoreduction peak occurs,
Spike potential is respectively-0.29V and-0.25V, and corresponding peak point current is respectively 6.8 μ A and-7.1 μ A,
According to vitamin B2Concentration linear with current peak, thus can solve and now electrolyte be tieed up
Raw cellulose content situation.
3, application platform connects signal situation
Fig. 7 is platform of the present invention and impedance test system use in conjunction schematic diagram.As it is shown in fig. 7, this base
External application interface in the portable potentiostat application platform 27 of vitamin B detection connects impedance and surveys
Test system 26, carries out control of Electric potentials and signal monitoring transmission to impedance test system, and RS485 transmits mould
Block 9 connects host computer 8 to carry out signal and controls output and process and show, be used for detecting attaching property biomembrane (as
Some antibacterial, cell etc.) situation such as area of attachment under different vitamine concentrations, adhesive force judges
Its upgrowth situation is with vitamine concentration situation of change.