WO2013081442A1 - Calcium sensing device and method of preparing thereof - Google Patents

Calcium sensing device and method of preparing thereof Download PDF

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Publication number
WO2013081442A1
WO2013081442A1 PCT/MY2012/000177 MY2012000177W WO2013081442A1 WO 2013081442 A1 WO2013081442 A1 WO 2013081442A1 MY 2012000177 W MY2012000177 W MY 2012000177W WO 2013081442 A1 WO2013081442 A1 WO 2013081442A1
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calcium
transducer
self
sensor
doped
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PCT/MY2012/000177
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French (fr)
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Alva Sagir
Rais Ahmad Mohd
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Mimos Berhad
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D165/00—Coating compositions based on macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain; Coating compositions based on derivatives of such polymers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/333—Ion-selective electrodes or membranes
    • G01N27/3335—Ion-selective electrodes or membranes the membrane containing at least one organic component
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/10—Definition of the polymer structure
    • C08G2261/12—Copolymers
    • C08G2261/122—Copolymers statistical
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/10—Definition of the polymer structure
    • C08G2261/14—Side-groups
    • C08G2261/142—Side-chains containing oxygen
    • C08G2261/1424—Side-chains containing oxygen containing ether groups, including alkoxy
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/10—Definition of the polymer structure
    • C08G2261/14—Side-groups
    • C08G2261/145—Side-chains containing sulfur
    • C08G2261/1452—Side-chains containing sulfur containing sulfonyl or sulfonate-groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
    • C08G2261/32—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain
    • C08G2261/322—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain non-condensed
    • C08G2261/3223—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain non-condensed containing one or more sulfur atoms as the only heteroatom, e.g. thiophene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/50—Physical properties
    • C08G2261/51—Charge transport
    • C08G2261/514—Electron transport
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/90—Applications
    • C08G2261/94—Applications in sensors, e.g. biosensors

Definitions

  • the present invention relates generally to beneficial compound detection device and methods, and more particularly to calcium detection device and methods.
  • calcium is the fifth element and the third most abundant metal in the earth's crust whereby it accounts for 3.64% of the earth's ' crust.
  • the distribution of calcium is very wide; it is found in almost every terrestrial area in the world. This element is essential for the life of plants and animals, as it plays a major role the growth of the animal's skeleton, in tooth, in the egg's shell, in the coral and in many soils. Seawater contains 0.15% of calcium chloride. Nevertheless, calcium cannot be found alone in nature. Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate.
  • calcium is always present in every plant, as it is essential for its growth. It is contained in the soft tissue, in fluids within the tissue and in the structure of every animal's skeleton.
  • the vertebrate's bones contain calcium in the form of calcium fluoride, calcium carbonate and calcium phosphate.
  • EDTA ethylenediaminetetraacetic acid
  • EDTA ethylenediaminetetraacetic acid
  • the ability of EDTA to potentially donate its six lone pairs of electrons for the formation of coordinate covalent bonds to metal cations like calcium makes EDTA a hexadentate ligand.
  • it measurement and detection of calcium ions in practice EDTA is usually only partially ionized, and thus forms fewer than six coordinate covalent bonds with metal cations.
  • EDTA forms an octahedral complex with most 2+ metal, cations, M 2+ , in aqueous solution.
  • the main reason that EDTA is used so extensively in the standardization of calcium solutions is that the formation constant for most calcium-EDTA complexes is very high, meaning that the equilibrium for the reaction:
  • methods use to determine the calcium ion concentration further includes atomic absorption spectroscopy (AAS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES) .
  • AAS atomic absorption spectroscopy
  • ICP-AES inductively coupled plasma atomic emission spectroscopy
  • titration or spectroscopy exhibits its own disadvatanges particulary when used for field adjations, because request more reagent, sample and big tools.
  • Ca-ISE Calcium ion-selective electrode
  • Ca-ISE Calcium ion-selective electrode
  • the application of Ca-ISE has evolved to a well establish routine analytical technique in ' many fields, including clinical, precision agriculture and environmental analysis.
  • Most of calcium ion-selective electrode used Ag/AgCl as transducer, but there are many disadvantages to decreased performance of Ca-ISE.
  • Dissolved carbon dioxide (C0 2 ) can react with water in the membrane to produced carbonic acid (H 2 C0 3 ) and oxidized Ag/AgCl electrode to make silver oxide layer. Silver oxide can prohibited electron transfer to Ag/AgCl surface and make electrode become unstable. The complete reaction following:
  • a calcium sensor electrode with self-doped polythiophene as a transducer layer Furthermore, we have demonstrated good responses and good linearity on miniaturized planar electrode. The results indicate that the disclosed can be deployed for detecting a wide range of calcium species in the fields. Calcium ion selective with polythiophenes layer can be packaged into a small wireless system and deployed for in-situ measurement of the analytes.
  • a calcium ion sensor with self- doped polythiophene nano-composite transducer comprising: at least one substrate for conductor layer seeding; at least one conductor to function as an electrical contact; a self-doped polythiophene transducer that functions as transducer layer for electron transfer; a carbon layer to function as a seeding substrate for the self-doped polythiophenes transducer layer; a calcium sensing membrane as a polymeric membrane and to function as calcium detector; and a retaining dam to hold calcium sensing membrane to not flood and carried out from surface area.
  • a method of preparing the calcium sensor with cast self- doped polythiophene nanocomposite transducer comprising the steps of: depositing carbon on electrode; preparing self-doped polythiophene nanocomposite casting solution; preparing calcium sensor cocktail composition; coating self-doped polythiophene nanocomposite solution on carbon electrode surface; coating calcium sensor cocktail on self-doped polythiophene transducer layer; and characterizing calcium sensor response.
  • FIG 1 shows a flowchart on the steps involved for preparing the ) sensor in accordance with the preferred embodiments of the present invention
  • FIG 2 shows the sensor in accordance with a preferred embodiment of the present invention.
  • FIG 3 shows the response versus activity of calcium ion shows good Nernstian response and good linearity, using the sensor of the present invention.
  • the present invention provides a calcium ion sensor. Furthermore,
  • the senor of the present invention shows good responses and good linearity on miniaturized planar electrode.
  • the results indicate that the disclosed can be deployed for detecting a wide range of calcium species in the fields.
  • Calcium ion selective with polythiophenes layer can be packaged into a small wireless system and deployed for in-situ measurement of the analytes.
  • FIG. 1 A schematic view of the method involved in preparing the calcium ion i sensor in accordance with the preferred embodiments of the present invention is shown in FIG 1.
  • I steps are: preparation of carbon electrode, preferably via screen printing method, that functions as a seeding substrate for self- doped polythiophenes transducer layer; preparation of self-doped polythiophenes conducting layer, preferably via chemically process, that functions as transducer layer for electron transfer;
  • the calcium ion sensor in accordance with the preferred embodiments of the i present invention comprises the following layers; at least one substrate which is preferably an inert material for conductor layer seeding; at least ' one conductor preferably metal and function as electrical contact; at least one carbon layer to function as a seeding substrate for self-doped polythiophenes transducer layer; a self-Doped polythiophene transducer that functions as transducer layer for electron transfer; a calcium sensing membrane is polymeric membrane and function as calcium detector; and a retaining dam formed as inert material and function to hold calcium sensing membrane to not flood and carried out from surface area.
  • the calcium sensor with cast self-doped polythiophene nanocomposite transducer preferably comprises 0.1 to 20% polythiophene, 0.1 to 20% dopant, 40 to 90% binder and 0.1 to 20% carbon nanotubes, all by weight; and the conducting polythiophene having the following structure:
  • R H, methyl, ethyl, butyl, pentyl, hexyl, heptyl, octyl
  • the dopant is at least one or combination of the following dopants; chloride, tetrafluoroborate, iodide, para- toluene sulfonate, trifluoromethane sulfonate, camphor sulfonate, poly styrene sulfonate, nafion, hexafluorophosphate .
  • calcium sensing membrane comprises; acrylic copolymer adhesive; forms homogenous blend with high molecular weight polymer and functions as adhesion promoter to solid electrode surface; high molecular weight polymer; functions as lipophilic polymeric matrix to allow transport of ionic species to electrochemical transducer surface; plasticizer; to soften the high molecular weight polymer in order to give flexible characteristic to the matrix; lipophilic additive; to create ionic sites within the polymer matrix to allow transport of ionic species; ion-recognizing molecule; to selectively bind with the analyte and to transport it across the membrane; at least one type of solvent; to homogenously dissolve all solid materials and for casting the cocktail composition on electrode surface.
  • the copolymer adhesive it is preferred that it comprises one part of methyl methacrylate monomer and at least one part of tetrahydrofurfuryl acrylate monomer by volume.
  • the copolymer may comprise of one part methyl methacrylate monomer and at least one part of n-butyl acrylate monomer by volume.
  • Carbon paste is screen printed on copper-gold or prefabricated screen printed silver.
  • printed carbon and silver are 100 micrometer.
  • the circular shaped electrodes with 3mm diameter is printed on polyester or printed circuit board substrate and separated by 2mm spacing from each other for integrated multi-sensor application.
  • the printed paste was cured at 120 °C to give the desired dry thickness.
  • Solder mask i insulating layer was also screen printed to define the electrode window, separate the wells and protect the printed conducting wires.
  • Calcium ion selective composition was prepared by mixing 28.2 mg poly (vinyl) chloride (PVC) , 3.1 mg copolymer methyl metha acrylate- n-butyl acrylate (MB28), 0.7 mg sodium tetrakis [bis
  • This calcium sensor was tested using commercial Ag/AgCl double junction reference electrode with 0.1M LiOAc as outer solution and calcium standard calibration solution at pH 6. Before tested, calcium sensor was soaked into 0.1 M calcium chloride at pH 6 until overnight to conditioning. The results were shown in TABLE 1 below and plotted in FIG 3. The plot of emf response versus activity of calcium ion shows good Nernstian response and good linearity.

Abstract

There is disclosed a calcium sensor comprising a transducer layer; sand sensor further comprises; at least one substrate for conductor layer seeding; at least one conductor tofunction as an electrical contact; a self-doped polythiophene transducer that functions as transducer layer for electron transfer a carbon layer to function as a seeding substrate for the self-doped polythiophenes transducer layer; a calcium sensing membrane as a polymeric membrane and to function as calcium detector; and a retaining dam to hold calcium sensing membrane to not flood and carried out from surface area.

Description

CALCIUM SENSING DEVICE AND METHOD OF PREPARING THEREOF
FIELD OF INVENTION
The present invention relates generally to beneficial compound detection device and methods, and more particularly to calcium detection device and methods.
BACKGROUND Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that this prior art forms part of the common general knowledge in Malaysia or any other country. Chemical sensing has become a significant aspect in resolving serious environmental challenges facing humankind aside from detection of useful compounds and much have been written about them. Gradually recognizing its potential to radically modify the living conditions of future generations has put forward various efforts to provide improved systems and methods for detecting the concentration of selected compounds within a sample.
An example of a compound known to provide astronomical health related benefits is calcium. Generally, calcium is the fifth element and the third most abundant metal in the earth's crust whereby it accounts for 3.64% of the earth's ' crust. The distribution of calcium is very wide; it is found in almost every terrestrial area in the world. This element is essential for the life of plants and animals, as it plays a major role the growth of the animal's skeleton, in tooth, in the egg's shell, in the coral and in many soils. Seawater contains 0.15% of calcium chloride. Nevertheless, calcium cannot be found alone in nature. Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate.
As discussed in the preceding paragraph, calcium is always present in every plant, as it is essential for its growth. It is contained in the soft tissue, in fluids within the tissue and in the structure of every animal's skeleton. The vertebrate's bones contain calcium in the form of calcium fluoride, calcium carbonate and calcium phosphate.
Various devices and methods have been developed for use in detecting the presence of calcium,' whereby typically complexometric titration with EDTA is widely used for calcium measurement. EDTA, ethylenediaminetetraacetic acid, has four carboxyl groups and two amine groups that can act as electron pair donors, or Lewis bases. The ability of EDTA to potentially donate its six lone pairs of electrons for the formation of coordinate covalent bonds to metal cations like calcium makes EDTA a hexadentate ligand. However, although it has been expedient it measurement and detection of calcium ions, in practice EDTA is usually only partially ionized, and thus forms fewer than six coordinate covalent bonds with metal cations. EDTA forms an octahedral complex with most 2+ metal, cations, M2+, in aqueous solution. The main reason that EDTA is used so extensively in the standardization of calcium solutions is that the formation constant for most calcium-EDTA complexes is very high, meaning that the equilibrium for the reaction:
Ca2+ + H4Y→ CaH2Y + 2H+
Figure imgf000005_0001
In many attempts to provide effective detection methods, a great majority are highly complex and rather cumbersome for users. In other cases, the methods lack precision. Typically, methods use to determine the calcium ion concentration further includes atomic absorption spectroscopy (AAS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES) . However, titration or spectroscopy exhibits its own disadvatanges particulary when used for field aplications, because request more reagent, sample and big tools.
Calcium ion-selective electrode (Ca-ISE) is the most commonly used as an alternative for calcium measurement in field. The application of Ca-ISE has evolved to a well establish routine analytical technique in ' many fields, including clinical, precision agriculture and environmental analysis. Most of calcium ion-selective electrode used Ag/AgCl as transducer, but there are many disadvantages to decreased performance of Ca-ISE. Dissolved carbon dioxide (C02) can react with water in the membrane to produced carbonic acid (H2C03) and oxidized Ag/AgCl electrode to make silver oxide layer. Silver oxide can prohibited electron transfer to Ag/AgCl surface and make electrode become unstable. The complete reaction following:
C02 + H20 H2C03 (1)
C03 2- + 2Ag+ - Ag2C03 (2) Ag2C03 * Ag20(s) + C02(g) (3)
In other methodologies, there is the introduction of polypyrrole doped with inorganic salt, commonly polypyrrole doped with KC1. But in fact, pyrrole monomer cannot perfectly mixture with inorganic salt solutions. This condition make not all pyrrole can completely polymerize during electropolymerize process and coat on electrode surface.
Considering the limitations of current methodologies, there is a need to identify a new method in detecting ammonium concentration so as to accommodate rapidly increasing demands.
Therefore this proposed calcium ion sensor will overcome the current disadvantages of conventional methods and devices.
In this disclosure there is provided a calcium sensor electrode with self-doped polythiophene as a transducer layer. Furthermore, we have demonstrated good responses and good linearity on miniaturized planar electrode. The results indicate that the disclosed can be deployed for detecting a wide range of calcium species in the fields. Calcium ion selective with polythiophenes layer can be packaged into a small wireless system and deployed for in-situ measurement of the analytes.
Further objects and advantages of the present invention may become apparent upon referring to the preferred embodiments of the present invention as shown in the accompanying drawings and as described in the following description.
SUMMARY OF INVENTION
In one aspect there is disclosed a calcium ion sensor with self- doped polythiophene nano-composite transducer comprising: at least one substrate for conductor layer seeding; at least one conductor to function as an electrical contact; a self-doped polythiophene transducer that functions as transducer layer for electron transfer; a carbon layer to function as a seeding substrate for the self-doped polythiophenes transducer layer; a calcium sensing membrane as a polymeric membrane and to function as calcium detector; and a retaining dam to hold calcium sensing membrane to not flood and carried out from surface area.
In another aspect of the present invention, there is provided a method of preparing the calcium sensor with cast self- doped polythiophene nanocomposite transducer comprising the steps of: depositing carbon on electrode; preparing self-doped polythiophene nanocomposite casting solution; preparing calcium sensor cocktail composition; coating self-doped polythiophene nanocomposite solution on carbon electrode surface; coating calcium sensor cocktail on self-doped polythiophene transducer layer; and characterizing calcium sensor response.
BRIEF DESCRIPTION OF DRAWINGS
Some figures contain color representations or entities. This invention will be described based on experimental results by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:
FIG 1 shows a flowchart on the steps involved for preparing the ) sensor in accordance with the preferred embodiments of the present invention;
FIG 2 shows the sensor in accordance with a preferred embodiment of the present invention; and
)
FIG 3 shows the response versus activity of calcium ion shows good Nernstian response and good linearity, using the sensor of the present invention.
> DETAILED DESCRIPTION
Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated ) element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.
The present invention provides a calcium ion sensor. Furthermore,
> the sensor of the present invention shows good responses and good linearity on miniaturized planar electrode. The results indicate that the disclosed can be deployed for detecting a wide range of calcium species in the fields. Calcium ion selective with polythiophenes layer can be packaged into a small wireless system and deployed for in-situ measurement of the analytes.
A schematic view of the method involved in preparing the calcium ion i sensor in accordance with the preferred embodiments of the present invention is shown in FIG 1.
Referring to FIG 1, the preparation of calcium ion selective with polythiophenes transducer membrane involves six main steps; these
I steps are: preparation of carbon electrode, preferably via screen printing method, that functions as a seeding substrate for self- doped polythiophenes transducer layer; preparation of self-doped polythiophenes conducting layer, preferably via chemically process, that functions as transducer layer for electron transfer;
> preparation of calcium sensing membrane, preferably by bulk or photopolerymerization methods, depend of calcium polymeric type; drop coat self-doped polythiophenes on carbon electrode surface as transducer layer; drop coat calcium selective membrane on self-doped polythiophenes transducer layer to make electrode selectively toward
I calcium present; and characterization of calcium selective electrode to make sure that electrode can detect calcium ion.
Proceeding from the above and now referring to FIG 2, the calcium ion sensor in accordance with the preferred embodiments of the i present invention comprises the following layers; at least one substrate which is preferably an inert material for conductor layer seeding; at least ' one conductor preferably metal and function as electrical contact; at least one carbon layer to function as a seeding substrate for self-doped polythiophenes transducer layer; a self-Doped polythiophene transducer that functions as transducer layer for electron transfer; a calcium sensing membrane is polymeric membrane and function as calcium detector; and a retaining dam formed as inert material and function to hold calcium sensing membrane to not flood and carried out from surface area.
In accordance with a preferred embodiment of the present invention, the calcium sensor with cast self-doped polythiophene nanocomposite transducer preferably comprises 0.1 to 20% polythiophene, 0.1 to 20% dopant, 40 to 90% binder and 0.1 to 20% carbon nanotubes, all by weight; and the conducting polythiophene having the following structure:
Figure imgf000011_0001
R = H, methyl, ethyl, butyl, pentyl, hexyl, heptyl, octyl
x = 0, 1 , 2, 3
v = 1. 2, 3, 4, 5, 6
Further in accordance with the preferred embodiments of the present invention, the dopant is at least one or combination of the following dopants; chloride, tetrafluoroborate, iodide, para- toluene sulfonate, trifluoromethane sulfonate, camphor sulfonate, poly styrene sulfonate, nafion, hexafluorophosphate . It is preferred that calcium sensing membrane comprises; acrylic copolymer adhesive; forms homogenous blend with high molecular weight polymer and functions as adhesion promoter to solid electrode surface; high molecular weight polymer; functions as lipophilic polymeric matrix to allow transport of ionic species to electrochemical transducer surface; plasticizer; to soften the high molecular weight polymer in order to give flexible characteristic to the matrix; lipophilic additive; to create ionic sites within the polymer matrix to allow transport of ionic species; ion-recognizing molecule; to selectively bind with the analyte and to transport it across the membrane; at least one type of solvent; to homogenously dissolve all solid materials and for casting the cocktail composition on electrode surface.
As for the copolymer adhesive, it is preferred that it comprises one part of methyl methacrylate monomer and at least one part of tetrahydrofurfuryl acrylate monomer by volume. In another embodiment, the copolymer may comprise of one part methyl methacrylate monomer and at least one part of n-butyl acrylate monomer by volume.
Below are examples on how the device of the present invention can be prepared. It shall be apparent to one skilled in the art that the exemplifications are provided to better elucidate the embodiments of the present invention and therefore should not be construed as limiting the scope of protection. All methods described as exemplifications herein may be performed in any suitable order unless otherwise indicated herein.
Example 1
Preparation of Screen Printed Carbon Electrode
Carbon paste is screen printed on copper-gold or prefabricated screen printed silver. The optimized dry thickness of both screen
) printed carbon and silver are 100 micrometer. The circular shaped electrodes with 3mm diameter is printed on polyester or printed circuit board substrate and separated by 2mm spacing from each other for integrated multi-sensor application. The printed paste was cured at 120 °C to give the desired dry thickness. Solder mask i insulating layer was also screen printed to define the electrode window, separate the wells and protect the printed conducting wires.
Example 2
Calcium ISE with Self-Doped Polythiophenes Transducer
)
Calcium ion selective composition was prepared by mixing 28.2 mg poly (vinyl) chloride (PVC) , 3.1 mg copolymer methyl metha acrylate- n-butyl acrylate (MB28), 0.7 mg sodium tetrakis [bis
3, 5 (trifluoromethyl) phenyl] borate (NaTFPB) , 1 mg Calcium Ionophore i IV, and 67 mg plasticizer o-NPOE . Mixture was dissolved with 1 mL tetrahydofuran (THF) solvent. Screen printed electrodes (SPE) with 4 mm diameter were cleaned ultrasonically with deionised water for 1 min. 10 microL Self-doped polythiophene cocktail was coat on SPE ^ and dried under N2 flow at 30 minutes. The homogenous calcium cocktail was drop coated on the freshly prepared self-doped polythiophenes layer and dried under continuous flow of nitrogen gas for 2 hours or air dried at ambient temperature for 12 hours. This calcium sensor was tested using commercial Ag/AgCl double junction reference electrode with 0.1M LiOAc as outer solution and calcium standard calibration solution at pH 6. Before tested, calcium sensor was soaked into 0.1 M calcium chloride at pH 6 until overnight to conditioning. The results were shown in TABLE 1 below and plotted in FIG 3. The plot of emf response versus activity of calcium ion shows good Nernstian response and good linearity.
Table 1: Response of Calcium ISE with self-doped polythiophenes conducting layer
Figure imgf000014_0001
It is understood by a person skilled in the art that the methods for experiments and studies are described as exemplifications herein and thus the results are not intended, however, to limit or restrict the scope of the invention in any way and should not be construed as providing conditions, parameters, agents or starting materials which must be utilized exclusively in order to practice the present invention. It is therefore understood that the invention may be practiced, within the scope of the appended claims, with equivalent methods for the experiments than as specifically described and stated in claims .

Claims

A calcium ion sensor with self- doped polythiophene nano- composite transducer comprising: at least one substrate for conductor layer seeding;
at least one conductor tofunction as an electrical contact;
a self-doped polythiophene transducer that functions as transducer layer for electron transfer
a carbon layer to function as a seeding substrate for the self-doped polythiophenes transducer layer;
a calcium sensing membrane as a polymeric membrane and to function as calcium detector; and
a retaining dam to hold calcium sensing membrane to not flood and carried out from surface area.
The calcium sensor as claimed in claim 1 wherein the doped polythiophene transducer comprises 0.1 to 20% polythiophene,
0.1 to 20% dopant, 40 to 90% binder and 0.1 to 20% carbon nanotubes, all by weight.
3. The calcium sensor as claimed in claim 1 wherein the conducting polythiophene having the following structure:
Figure imgf000016_0001
R = H, methyl, ethyl, butyl, pentyl, hexyl, heptyl, octyl
x = 0, 1 , 2, 3
V = 1 , 2, 3, 4, 5, 6 The calcium sensor as claimed in claim 1 wherein the dopant is at least one or combination of the following dopants; chloride, tetrafluoroborate, iodide, para-toluene sulfonate, trifluoromethane sulfonate, camphor sulfonate, poly styrene sulfonate, nafion, hexafluorophosphate .
The calcium sensor as claimed in claim 1 wherein the calcium sensing membrane comprising; a high molecular weight polymer; functions as lipophilic polymeric matrix to allow transport of ionic species to electrochemical transducer surface;
acrylic copolymer adhesive; which blends with the high molecular weight polymer and functions as adhesion promoter to solid electrode surface;
plasticizer; to soften the high molecular weight polymer in order to give flexible characteristic to the matrix;
lipophilic additive; to create ionic sites within the polymer matrix to allow transport of ionic species;
ion-recognizing molecule; to selectively bind with the analyte and to transport it across the membrane; and
solvent; to homogenously dissolve all solid materials and for casting the cocktail composition on electrode surface.
The calcium sensor as claimed in claim 5 wherein the copolymer comprises one part of methyl methacrylate monomer and at least one part of tetrahydrofurfuryl acrylate monomer by volume. The calcium sensor as claimed in claim 5 wherein the copolymer comprises 1 part of methyl methacrylate monomer and at least 1 part of n-butyl acrylate monomer by volume.
A method of preparing the calcium sensor with cast self- doped polythiophene nanocomposite transducer comprising the steps of: depositing carbon on electrode;
preparing self-doped polythiophene nanocomposite casting solution;
preparing calcium sensor cocktail composition;
coating self-doped polythiophene nanocomposite solution on carbon electrode surface;
coating calcium sensor cocktail on self-doped polythiophene transducer layer; and
characterizing calcium sensor response.
The sensor as claimed in Claim 1 used in at least one of the following applications; precision agriculture, food sensors, medical sensors.
PCT/MY2012/000177 2011-12-01 2012-06-29 Calcium sensing device and method of preparing thereof WO2013081442A1 (en)

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MYPI2011005813 2011-12-01

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WO2014092543A1 (en) * 2012-12-11 2014-06-19 Mimos Berhad A calcium ion selective sensor
CN104849335A (en) * 2015-05-29 2015-08-19 李宏奎 Method for detecting ionic calcium content of blood sample

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014092543A1 (en) * 2012-12-11 2014-06-19 Mimos Berhad A calcium ion selective sensor
CN104849335A (en) * 2015-05-29 2015-08-19 李宏奎 Method for detecting ionic calcium content of blood sample

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