Eiji Niki

Preparation of Na+-selective electrodes by ion-implantation of lithium and silicon into single-crystal alumina wafer and its application to the production of ISFET

ZusammenfassungNa+-selektive Elektroden wurden durch Einbau von Si+ und Li+ in Aluminiumoxidblättchen hergestellt und ihre Charakteristiken untersucht. Die Blättchen hatten eine Dicke von 100 μm und einen Durchmesser von 1,40 cm. Ebenso wurde die Membran für einen ISFET hergestellt. Die Gesamtmenge von Li+ und Si+ wurde auf 1013–1015 Ionen/cm2 eingestellt, wobei sich bei 1014 oder 4×1014 Ionen/cm2 die beste Charakteristik ergab.Die Responsekurven der mit 1014 Ionen/cm2 versehenen Aluminiumoxidplättchen hatten eine Neigung von 42 mV/pNa in einem Konzentrationsbereich von 1–10−4mol/l. Der nach 1 min erhaltene volle Response war reproduzierbar. Die vorgeschlagene Technik wurde zur Einstellung der Gate-Oberfläche des Feldeffekt-Transistors auf Natriumion benutzt. Der Na+-sensitive FET (Na+-ISFET), der durch Einbau von Li+ und Al+ mit 5×1014 Ionen/cm2 hergestellt wurde, zeigte eine Neigung der Signalkurve von 30 mV/pNa in einem Bereich von 1–10−4mol/l.SummarySodium ion-selective electrodes (Na+-ISE) were prepared by implanting Si+ and Li+ into alumina wafers and their characteristics were investigated. The alumina wafer had a thickness of 100 μm and a diameter of 1.40 cm. The ionselective membrane was produced by ion-implanting of Li+ and Si+ on both sides of a single-crystal alumina wafer. The total doses of Li+ and Si+ were controlled to be the same, viz. 1013–1015 ions/cm2. The ion-implanted alumina wafer with 1014 or 4×1014 ions/cm2 of Li+ and Si+ showed better characteristics than the others.The response curves of the 1014 ions/cm2 implanted alumina wafer had a slope of 42 mV/pNa in a concentration range from 1–10−4mol/l. The full response achieved after about 1 min was reproducible. The proposed idea of producing Na+-ISE by ion-implantation technique was applied to functuate the gate surface of the field effect transitor to sodium ion. The sodium ion-sensitive FET (Na+-ISFET) prepared by implanting Li+ and Al+ at a dose of 5×1014 ions/cm2 showed a slope of 30 mV/pNa in a concentration range from 1–10−4mol/l.

An improved alternating current polarograph

Abstract Results obtained with the a.c. bridge polarograph devised by the authors are given.

Studies on continuous coulometric titration: I. Fundamental principles of an automatic coulometric titrator

Abstract An automatic continuous coulometric titrator has been constructed, which, continuously analyses the concentration of the reducible component in a stream of sample solution by recording the electrolytic d.c. current, which is controlled so that the electrolytically generated bromine can just be titrated. The voltage indicated in the titration cell is picked up as a signal and converted to a.c. voltage. After rectification and amplification, it is used as the generating d.c. current. This amplified d.c. current controls the generating d.c. current in proportion to the concentration of the reducible component in the sample solution. The theoretical relationship between the concentration of the reducible component and the intensity of the electrolytic current is discussed, taking into consideration the effect of the excess free bromine in the reaction cell upon the input of the d.c. amplifier.

Some developments in recording polarography

Abstract The polarograph has developed in step with the progress of the recorder. To-day numerous polarographs exist with pen-writing recorders, such as the photo-pen type, the ammeter type with d.c. amplification, and the potentiometer type with automatic balance. The recording polarograph with compensating bridge is now widely used in Japan, and continues to displace the conventional instrument.

Accuracy and precision of an absorbancy-linear spectrophotometer

比色法における光電比色計において,メーターの目盛が,吸光度Aを線形表示とした吸光度A線形光電比色計を試作した.さらに吸光度A線形表示における,メーターの読み取り誤差,ゼロ合わせ誤差,フルスケール合わせ誤差,吸光度範囲切り替え法における誤差などを検討し,従来の透光度T線形表示の誤差と比較した.吸光度A線形表示におけるメーターの各誤差に対する吸光度Aの相対誤差は,読み取り誤差では1/A,ゼロ合わせ誤差では1/A,フルスケール合わせ誤差では(1-A)/Aで示される.それらを総合した誤差において,Aが大きくなるほど,誤差は小さくなる.吸光度範囲切り替え法における読み取り誤差では,Aの相対誤差は1/(A+A1)で示される.これらは実験でも証明された.

Study on Construction of Self-recording Spectrophotometer.

著者らはBeckman DU型分光光度計に付加するためにさきに試作した自動記録装置の電気的回路について検討した。すなわち,回路の各部における信号の波形をオッシロスコープによって観測するとともに,回路の直線性を測定した。回路の要点は3極管を使用した同期整流回路にあるが,記録値が試料濃度と直線関係を保つためには,3極管の動作状態を適当に選ばねばならない。3極管の陽極電庄を10Vとしたとき,1.65Vのバイアスでほぼ満足すべき直線性が得られた。種々濃度の過塩素酸コバルトおよび硝酸ニッケル水溶液について吸収曲線を記録し,透過率10%以上の範囲で記録値は試料濃度と比例関係を保った。