Shin-ichi Wakida

Phosphate ion-sensitive coated-wire/field-effect transistor electrode based on cobalt phthalocyanine with poly(vinyl chloride) as the membrane matrix

Abstract An ion-selective coated-wire/field-effect transistor electrode responding to dihydrogenphosphate is described. The device consists of a coated-platinum wire electrode connected to the gate of a conventional field-effect transistor. Cobalt phthalocyanine is used as ion-exchange electroactive substance and poly(vinyl chloride) as the membrane matrix. The characteristics of the device are investigated and its response is studied by two methods, the linear dependence of the square root of the drain current in the saturated region on the logarithm of ion activity for sodium dihydrogenphosphate, and the dependence of the gate-source potential on the logarithm of ion activity of the same ion. A linear response is obtained in the range of ion activity 10−5-10−1 mol dm−3 and the response slope is 45 mV per decade change of H2PO4− ion activity; the selectivity coefficients are discussed.

Separation of aniline derivatives by micellar electrokinetic chromatography

Abstract The separation of ten aniline derivatives was investigated by micellar electrokinetic chromatography. The pH dependence of their migration behaviour wa

Effect of alkyl chain length of sodium N-acyl sarcosinates on migration behavior in micellar electrokinetic chromatography

Application of sodium N-acyl sarcosinates for micellar electrokinetic chromatography was investigated. Three homologous sodium N-acyl sarcosinates were able to be used as pseudo-stationary phase. The migration behavior of some aromatic test samples was investigated with these surfactants under the same micellar concentrations. The migration time window became wider as the alkyl chain length of surfactant decreased. The capacity factors increased with an increase in the alkyl chain length of surfactant. Three sarcosinates gave almost the same separation selectivity for hydrophilic solutes. The separation selectivity for hydrophobic solutes was slightly different from one another.

Urushi matrix sodium, potassium, calcium and chloride-selective field-effect transistors

Abstract Sodium, potassium, calcium and chloride ion-selective field-effect transistors (ISFETs) with Urushi (natural oriental lacquer) matrix membrane were fabricated. The Urushi matrix ISFETs have good stability and durability for over a month because of the strong adhesion of the Urushi matrix membrane to the Si3N4 gate. The sensitivity, linear response range and selectivity of the Urushi matrix ISFETs are coincident with those of the corresponding polyvinylchloride (PVC) matrix ion-selective electrodes. The hardening mechanism and the matrix mechanism of the Urushi matrix membrane are discussed.

A novel urushi matrix sodium ion-selective field-effect transistor

Abstract A durable sodium ion-selective field-effect transistor (ISFET) is proposed with Urushi as the membrane matrix. The sodium ion-sensing membrane is composed of sodium ionophore (ETH 227), di-2-ethylhexylphthalate, potassium tetrakis(p-chlorophenyl)borate and Urushi. The prepared Urushi matrix ISFET showed a linear response in the sodium ion activity range from 100 M to 10−3.5 M and about 53 mV per decade change of sodium ion activity. The selectivity of the Urushi matrix ISFET was almost the same as that of the corresponding PVC matrix ion-selective electrode. The Urushi ISFET showed excellent stability with drift below 0.15 mV per hour and durability for over a month, because of strong adhesion of the membrane to the Si3N4 gate.

A novel Urushi matrix chloride ion-selective field effect transistor

A durable chloride ion-selective field effect transistor (ISFET) is proposed with Urushi as the membrane matrix. The chloride ion-sensing material is a quaternary ammonium chloride: trioctylmethylammonium chloride (TOMA-Cl) or tridodecylmethylammonium chloride (TDMA-Cl). The optimum composition of the Urushi membrane was found by use of Urushi ion-selective electrodes. The mixture with the most favourable composition was coated on the gate region of the FET device. The Urushi ISFET with TDMA-Cl proved to be superior to that with TOMA-Cl, in sensitivity, linearity and selectivity. The Urushi ISFET with TDMA-Cl showed a linear response of about -51 mV per decade change of chloride ion activity in the range 10(-4)-1M. The Urushi ISFET showed excellent stability and durability for over two months, because of strong adhesion of the membrane to the Si(3)N(4) gate.

Chemically Modified Copper Hybrid Ion Sensor with 7,7,8,8,-Tetracyanoquinodimethane

A copper hybrid ion sensor modified with 7,7,8,8,-tetracyanoquinodimethane (TCNQ) is proposed as a preparation method of an ion sensing membrane. The copper coated lead-wire ion selective field-effect transistor (CLISFET) with a copper TCNQ anion radical complex film showed a linear response of about 30 mV per decade change of copper ion activity (almost a theoretical Nernstian slope) in the range from 10-5 M to 10-1 M. Ag+, Hg2+ and S2- interfered with Cu(TCNQminusdu) film. However, the selectivity coefficients for other ions were below 10-2.5. The copper CLISFET gave a stable potential response after a slight initial drift during 2.5 hours. The response time of the copper CLISFET was less than 10 seconds from low to high concentrations; in the reverse case, the response time became less than 30 seconds as a result of the memory effect.

Methods for the preparation and characterisation of a selenocyanate ion-sensitive field effect transistor with Urushi as the membrane matrix

A selenocyanate ion-sensitive field effect transistor (ISFET) was fabricated from a silicon wafer with Urushi (natural lacquer) as the membrane matrix. The proposed ion sensor has excellent durability for over 2 months. The ISFET can be characterised by the relationship between the square root of the drain current and the logarithm of the ion activity in the saturation region of the ISFET. It was found that the linear response range of the Urushi ISFET was from 10–5 to 10–1M selenocyanate ion activity and the selectivity coefficients were almost the same as those of the Urushi ion-selective electrode.

Evaluation of Mental Workload for Athletes' Training Based on Salivary NO3- Concentration

We think that salivary NO3- concentration corresponds to mental workload. To confirm that, so far we have a lot of experiments for navigators in handling-a-ship simulator, which can be arranged an experiments surroundings. Through this experiment, we trust in the effectiveness of salivary NO3- concentration as a physiological index, because the salivary NO3- has a special characteristic to show quick response to mental workload on the spot and such trend as moving average. On the other hand, we confirm the effectiveness of a variety of physiological indices, heart rate variability (R-R interval), nasal temperature, and salivary amylase as well as salivary NO3- concentration, but these are not good at giving us a response of mental workload instantly because these physiological indices need to analyse numerical values from data. After all, to evaluate mental workload quantitatively by salivary NO3- concentration helps younger navigators to grasp the handling-a-ship skill of veteran navigators, in concrete terms younger navigators understand the risky handling-a-ship situations from mental workload veteran navigators feel. As mentioned earlier, salivary NO3- concentration is a good index to measure mental workload, however, actually measurement errors by this index occur in experiments. So in this paper, we confirm one of the errors, occurred by exercise, and can decrease the error.

A new selenocyanate-selective electrode based on an Urushi matrix-membrane

ZusammenfassungEine Selenocyanat-selective Elektrode wurde aus einem Tri-n-octylmethylammonium-Selenocyanat-Austauscher und einer Urushi-Matrix hergestellt. Lineare Potential-Konzentrations-Kurven wurden im Konzentrationsbereich 10−1 bis 10−5 mol/l Selenocyanat erhalten. Bei Einsatz von 45–50% Tri-n-octylmethylammonium-Selenocyanat und 55-50% rohem Urushi-Latex betrug die Neigung des linearen Teils der Potential-Konzentrationskurve 60 mV pro Zehnerpotenz Selenocyanatkonzentration. Die statische Ansprechzeit war weniger als 30 s. Die Elektrode wies im pH-Bereich von 2–10 ein konstantes Potential auf. Der Selektivitätskoeffizent wurde nach der Methode der Lösungsgemische gemessen. Die Elektrode wurde angewendet zur Messung der Bildung von Selenocyanat aus seleniger Säure, Ascorbinsäure und Kaliumcyanid.SummaryA selenocyanate-selective electrode was prepared from tri-n-octylmethylammonium selenocyanate ion-exchanger and a matrix, Urushi. A linear potential-concentration curve was obtained within the concentration range of 10−1–10−5 mol/l selenocyanate. When 45–50 wt% of trin-octylmethylammonium selenocyanate ion-exchanger and 55-50 wt% of raw Urushi latex were used, the slope of the linear part of the potential-concentration curve was 60 mV per decade change of the selenocyanate concentration. The static response time was less than 30 s. The electrode exhibited constant potential within the pH range 2–10. The selectivity coefficient for the electrode was measured with the mixed solution method. The electrode was used for the measurement of the formation of selenocyanate from selenious acid, ascorbic acid and potassium cyanide.