Integrated multi-sensor chip with photocured polymer membranes containing copolymerised plasticizer for direct pH, potassium, sodium and chloride ions determination in blood serum

An analytical system based on a sensor array with ion-selective field effect transistors (ISFETs) monolithically integrated in one chip covered with photocured polymer membranes containing copolymerised plasticizer and a sequential injection analysis (SIA) is shown to offer an automation of the analysis of blood serum components. For sequential injection system a custom made dual channel flow cell for the sensor array was developed. Optimisation of ion-sensitive membrane characteristics and calibration solution compositions were carried out. The system was used to analyze sodium, potassium, chloride ion contents in blood serum samples. The precision of the ion determination in samples was typical for potentiometic method with standard deviation of about 3-5%.     

Highly selective iodide-sensing silicone ladder polymer membranes containing a porphyrin and a quaternary ammonium salt.

It has been demonstrated that a glass-like silicone ladder-type polymer permits one to homogeneously incorporate high amounts of ionophores into the covalently-bonded double chain structure. Furthermore, by making use of this feature, we have successfully fabricated an iodide ion-sensitive field-effect transistor based on two kinds of ionophores and silicone ladder polymer matrix. As ionophores, 5,10,15,20-tetraphenyl-21H,23H-porphyrin and dimethyloctadecyl-3-trimethoxylsilylpropylammonium chloride were homogeneously incorporated into the matrix. The ion-sensitive field-effect transistor showed a linear potential response ranging in the I- concentration between 1.0 x 10(-5) and 1.0 x 10(-1) M. The selectivity coefficients for I- towards interferences of ClO4- and NO3- were estimated to be Kpot(I-,ClO4-) approximately 6.2 x 10(-4) and Kpot(I-,No3-) approximately 4.9 x 10(-4). The matrix has proved to be so stable that the selectivity coefficients have not been altered over six months.     

Development of a new matrix based on a silicone ladder polymer for ion-sensing membranes.

A silicone ladder-type polymer was successfully utilized for a matrix of an ion sensing membrane to fabricate an ion-sensitive field-effect transistor. An ion sensing membrane was readily fabricated by mixing a silicone ladder-type oligomer with a quaternary ammonium salt, casting onto the gate of the field-effect transistor, and polymerizing with heating. Since no acid catalysts were needed to prepare the ion sensing membrane, it was possible to keep the quaternary ammonium salt in the matrix without decomposition. The ion-sensitive field-effect transistor based on the silicone ladder-type polymer and the quaternary ammonium salt showed a linear response with a slope of -58.1 mV decade(-1) very close to the theoretical Nernstian response over an NO3- range between 3.0 x 10(-6) and 1.0 x 10(-1) M. The time required to reach 90% total response was within 5 s, when the NO3- concentration was changed from 1.0 x 10(-3) to 3.0 x 10(-3) M. The newly fabricated ion-sensitive field-effect transistors have kept their original sensitivity for more than half a year.     

Applied potential and radiotracer studies on poly(vinyl chloride) matrix ion-selective electrode membranes

This paper reports the effect of applied potentials on PVC matrix membranes containing (i) the barium ion-sensitive barium-Antarox C0880 complex and 2-nitrophenyl phenyl ether solvent mediator, and (ii) the calcium ion-sensitive Orion 92-20-02 phosphate-based calcium liquid ion-exchanger. Platinum electrodes were placed in solutions on each side of the membranes. The barium ion-sensitive membranes are unable to maintain stable current flows but the calcium ion-sensitive membranes are characterized by stable current flows over prolonged periods even after successive polarity reversals. Results are presented, from radiotracer experiments for permeation of ions through the membranes with and without an applied potential. No evidence was found for significant permeation of barium-133 ions through the barium ion-sensing membranes into an initially inactive solution, but it was found that barium-133 ions were incorporated into the membranes after removal of the applied potential. Permeation of sodium-22 ions through the calcium ion-sensing membranes occurred only to a limited extent in the presence of an applied potential and not at all in its absence, confirming electrode selectivity trends for calcium and sodium. Calcium-45 ions did not permeate the calcium ion-sensing membranes into an inactive counter-solution against the potential gradient, but on reversal of the polarity, permeation occurred to a far greater extent than in the absence of an applied potential. These differences in behaviour are compatible with the more complicated membrane pathways of the barium ion-sensing membranes, imposed by the complexing of barium ions by the ethyleneoxy units of Antarox C0880 in a tight helical conformation. The calcium ion-sensing membranes are much less constrained, thus permitting more facile replacement of the calcium ions in the membrane by ions from solution.     

基于磁性分子印迹聚合物的电化学传感器的研究进展

分子印迹聚合物与磁性纳米材料结合,制备成磁性分子印迹纳米敏感膜,这样做不仅可以发挥分子印迹聚合材料的优势,而且磁性纳米粒子可有效提高电化学传感器的灵敏度、稳定性以及生物相容性等。近年来将磁性分子印迹纳米敏感膜应用于电化学传感器制备成的磁性分子印迹电化学传感器得到了较快的发展。本文就近5年来磁性分子印迹电化学传感器敏感膜所用的磁性材料、敏感膜制备方法以及磁性分子印迹电化学传感器在环境、食品以及临床方面的应用进行了综述总结。     

Development of microbiosensors

Semiconductor fabrication technology was used for development of ion sensitive field effect transistor (ISFET) and micro-electrodes which have been utilized as transducers of enzyme-based microbiosensors. A urea sensor consisted of two ISFETs; one ISFET is urease-coated ISFET and the other ISFET is reference ISFET. A linear relationship was obtained between the initial rate of voltage change and the logarithm of urea concentration over the range 1.3 to 16.7 mM. ATP and hypoxanthine sensors were also developed utilizing ISFET as a transducer. Furthermore, microelectrodes such as hydrogen peroxide and oxygen sensors were prepared by the silicone fabrication technology. A glucose sensor consisted of a hydrogen peroxide electrode and immobilized glucose oxidase membrane. A linear relationship was observed between the current increase and the concentration of glucose (1–100 mg dl⁻¹). A microoxygen electrode was constructed from Au electrodes, polymer matrix containing alkaline electrolyte and a photocross-linkable polymer membrane. This electrode was used as a transducer in microglucose sensor. A microglutamic acid sensor is also described.     

Fluorometric sensors based on chemically modified enzymes Glucose determination in drinks

In this paper an enzymatic fluorometric sensor for glucose determination in drinks is presented. The sensor film was obtained by immobilisation of glucose oxidase chemically modified with a fluorescein derivative (GOx-FS) in a polyacrylamide polymer. During the enzymatic reaction the changes in the fluorescence intensity of the GOx-FS are related to the glucose concentration. Working in FIA mode, the optimum conditions found were: 0.7 ml min(-1) flow rate, 300 mul sample injection and pH 6.5. The sensor responds to glucose concentrations ranging from 400 to 2000 mg l(-1), the reproducibility is around 3% and the life-time is at least 3 months (more than 350 measurements). The sensor was applied to direct glucose determination in drinks with good accuracy; interference caused by the filter effect was avoided by the kinetics of the reaction.     

Solid state biosensors using thin-film electrodes

Solid-state technology was used to fabricate a new type of glucose sensor and a differential measurement system was incorporated with the sensor in order to suppress interfering signals. This glucose sensor was composed of film electrodes and an enzyme-immobilizing membrane. The hydrogen peroxide electrodes were fabricated by metallic film deposition. Glucose oxidase (GOD), an enzyme, was immobilized in photosensitive polyvinyl alcohol to enable the enzyme-immobilizing membrane to be formed by the usual photolithographic method. Two anodes and one common cathode were formed on a glass substrate. One of the anodes was coated with PVA containing active enzyme and the other with PVA containing deactivated enzyme. By setting up a differential output measurement system, it was possible to suppress the interfering signals that might be generated by some other reducing substances in a sample solution. With this measuring technique, the signal of ascorbic or uric acids up to 100 mg/dl was successfully cancelled. Glucose concentrations in the range 5 to 100 mg/dl could be detected by the present sensor.The fabrication processes of the present sensor were so compatible with IC technology that it should be possible to mass produce disposable glucose biosensors using IC fabrication techniques.     

声表面波化学传感器膜材料的研究进展

声表面波(Surface Acoustic Wave,简称SAW)化学传感器是一种可用于现场实时检测的气敏传感器,具有体积小、选择性好、信号响应快等特点,其中敏感膜材料是决定其性能的关键因素。本文主要介绍了传感器的工作原理,敏感膜与吸附气体之间的作用力,对膜材料的选择及性能影响因素进行了详细阐述。重点介绍了现有膜材料的分类及应用,主要有有机聚合物膜、无机物膜、超分子膜和复合膜,比较了它们的优缺点。对现有成果进行总结,同时提出了传感器膜材料的发展趋势。     

基于荧光内滤效应的荧光增强型钠离子光纤传感器

在吸收型钠离子光化学传感器的敏感膜中加入合适的荧光试剂,应用荧光内滤效应研制成的荧光增强型光纤传感器,在测量灵敏度和抗背景干扰能力方面均有较大的改善,对血清和矿泉水样品中的钠离子含量进行了分析,获得了满意的结果。     

新型成膜法的SAW气体传感器聚合物膜的粘弹性分析

An analysis of the response of surface acoustic wave sensors coated with polymer film based on new coating deposition (self-assemble and molecularly imprinted technology) is described and the response formulas are hence deduced. Using the real part of shear modulus, the polymer can be classified into three types: glassy film, glassy-rubbery film and rubbery film. Experimental results show that the attenuation response is in better consistence with the simulation than in Martin's theory, but the velocity response does not accord with the calculation exactly. Maybe it is influenced by the experimental methods and environment. In addition, simulations of gas sorption for polymer films are performed. As for glassy film, the SAW sensor response increases with increasing film thickness, and the relationship between the sensor response and the concentration of gas is pretty linear, while as for glassy-rubbery film and rubbery film, the relationship between the sensor sensitivity and concentration of gas is very complicated. The ultimately calculated results indicate that the relationship between the sensor response and frequency is not always linear due to the viscoelastic properties of the polymer.     

A wireless pH sensor using magnetoelasticity for measurement of body fluid acidity.

The determination of body fluid acidity using a wireless magnetoelastic pH-sensitive sensor is described. The sensor was fabricated by casting a layer of pH-sensitive polymer on a magnetoelastic ribbon. In response to an externally applied time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic frequency that is inversely dependent upon the mass of the pH polymer film, which varies as the film swells and shrinks in response to pH. As the magnetoelastic sensor is magnetostrictive, the mechanical vibrations of the sensor launch magnetic flux that can be detected remotely using a pickup coil. The sensor can be used for direct measurements of body fluid acidity without a pretreatment of the sample by using a filtration membrane. A reversible and linear response was obtained between pH 5.0 and 8.0 with a measurement resolution of pH 0.1 and a slope of 0.2 kHz pH(-1). Since there are no physical connections between the sensor and the instrument, the sensor can be applied to in vivo and in situ monitoring of the physiological pH and its fluctuations.     

Recovery of anionic surfactant by RO process. Part II. Fabrication of thin film composite membranes by interfacial reaction

A new technique has been established to fabricate thin film composite membranes, by which a hydrophilic polymer could be coated in thin film on a hydrophobic support membrane. The new technique was composed of two steps: dispersion of a reactant to the hydrophilic polymer in the hydrophobic support membrane and interfacial reaction between the reactant and the hydrophilic polymer to produce thin film of the hydrophilic polymer on the support membrane. Composite membranes in which a thin film of sodium alginate is coated on a polysulfone support membrane were prepared by the new technique for the reverse osmosis separation of anionic surfactant–water mixture. Two methods were employed to fabricate a thin film of sodium alginate on the support membrane: (1) dispersion of the crosslinking agent, CaCl₂ alone in the support membrane and (2) dispersion of CaCl₂ in the support membrane with help of PVA which adheres fast to the support membrane. The formation mechanism of the thin layer was suggested schematically on each method. Both the methods could produce successively a thin layer of SA on the support membrane. Especially, method (2) gave a strong bonding of the thin layer on the support because of the large contact area with the support through the PVA layer which sticks fast to the SA layer. From the SEM pictures and permeation experiments, the method (2) was confirmed to be better to produce a defect-free thin film of SA on the support membrane.     

Glucose-sensitive field-effect transistor with a membrane containing co-immobilized gluconolactonase and glucose oxidase

A glucose-sensitive field-effect transistor (FET) with a two-enzyme membrane containing gluconolactonase and glucose oxidase is investigated. The two-enzyme membrane (ca. 1 μm thick) is formed on the ion-sensitive gate of the FET by photopolymerization. The gluconolactonase used was a partially purified product prepared from crude glucose oxidase by gel filtration. A glucose sensor with only purified glucose oxidase has little response for glucose, but the co-immobilization of gluconolactonase and glucose oxidase considerably enhanced the response amplitude of the glucose sensor. The composition of the two-enzyme/photopolymer solution is optimized; gluconolactonase with an activity at least twice that of glucose oxidase is necessary. The linear calibration graph extends from 0.2 to 2 mM glucose.     

Preparation of refractive index matching polymer film alternative to oil for use in a portable surface-plasmon resonance phenomenon-based chemical sensor method

In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction.     

A Graphite Coated Membrane Electrode in Drug Analysis

This paper describes the preparation of a graphite electrode coated with membrane containing the dibutyl phthalate (or dioctyl phtalate) as the plasticizer and poly (vinyl chloride) as the polymer matrix.The test has shown this coated membrane graphite electrode can be used as a indicator electrode in potentionmetry titration.lt is accurate, precise and sharp end-point jump when titrate drugs with sodium tetraphenbor. This method is more simple and convenient and rapid than the pharmacopoeia method.     

Characteristics of a surface plasmon resonance sensor combined with a poly(vinyl chloride) film-based ionophore technique for metal ion analyses.

The characteristics of a surface plasmon resonance (SPR) sensor prepared by coating a metal film evaporated on a prism with a polymer film containing tetra-n-butyl thiuram disulfide (TBTDS) were studied. The differences in the sensitivity, selectivity, and detection limit for a Zn2+ ion of the SPR sensor were reported as a function of the thickness of the polymer film, the kind of a metal film, and the kind of a polymer film. The thinner was the polymer film, the higher was the sensitivity, and the lower was the detection limit. The Ag film gave to the SPR sensor higher sensitivity than the Au film. TBTDS contained in the poly(vinyl chloride) (PVC) film slightly improved the selectivity toward the Zn2+ ion. A non-conditioned poly(methyl methacrylate) (PMMA) film containing TBTDS gave a lower detection limit of 1.0 x 10(-6) mol/l, which is similar to that obtained by using an ion selective electrode (ISE) method, than the PVC film. The PVC film, however, gave higher concentration resolution than the PMMA film.     

Alcohol-FET sensor based on a complex cell membrane enzyme system

An alcohol -FET sensor was developed by use of a complex enzyme system in a cell membrane and an ion-sensitive field effect transistor (ISFET). The cell membrane of Gluconobacter suboxydans IFO 12528, which converts ethanol to acetic acid, was immobilized on the gate of an ISFET with calcium alginate gel coated with nitrocellulose. This ISFET (1), a reference ISFET without the cell membrane (ISFET 2) and an Ag/AgCl reference electrode were placed in 5 mM Trismalate buffer (pH 5.5, 25°C), and the differential output between ISFETS 1 and 2 was measured. The output of the sensor was stabilized by adding pyrroloquinoline quinone. The response time was ca. 10 min., and there was a linear relationship between the differential output voltage and the ethanol concentration up to 20 mg l^?1. The output of the sensor was stable for 40 h below 30°C. The sensor responded to ethanol, propan- 1-ol and butan- 1-ol, but not to methanol, propan-2-ol and butan-2-ol. The sensor was used to determine blood ethanol.     

Reference field effect transistors based on chemically modified ISFETs

Different hydrophobic polymers were used for chemical modification of ion-sensitive field effect transistors (ISFETs) in order to prepare a reference FET (REFET). Chemical attachment of the polymer to the ISFET gate results in a long lifetime of the device. Properties of polyacrylate (polyACE) REFETs are described in detail. The polyACE-REFET is superior to other polymer modified REFETs, showing an excellent pH insensitivity (?1 mV pH^?1), a long lifetime and an electrically identical behaviour as an unmodified pH ISFET or a cation-selective PVC-MEMFET (membrane FET). The cation permeselectivity of the polymer can be significantly reduced by addition of immobile cations. The applicability of a polyACE-REFET in differential measurements with a pH ISFET and a K⁺ MEMFET is demonstrated.     

Ascorbic acid sensor based on ion-sensitive field-effect transistor modified with MnO2 nanoparticles

An ascorbic acid (AA) sensor based on an ion-sensitive field-effect transistor (ISFET) was prepared by modifying the sensitive area of the transducer with MnO₂ nanoparticles. An additional Nafion membrane coated on top of the sensor was used to immobilize the MnO₂ nanoparticles and restrict the amount of ascorbic acid entering the membrane. The reaction of the MnO₂ nanoparticles with ascorbic acid produced a local pH change, which was correlated with the ascorbic acid concentration and could be monitored by the ISFET. The linear range of the ascorbic acid sensor was 0.02-1.27 mM, and the detection limit was 0.01 mM. The effects of buffer concentration, pH, and ionic strength on the sensor performance were also examined. In addition, the sensor has good stability and reproducibility, and the construction and renewal of the sensor are simple and inexpensive.