Yasuyoshi Matsumoto

A micro-planar amperometric glucose sensor unsusceptible to interference species

Abstract The development of an amperometric glucose sensor in which a hydrogen peroxide detecting platinum electrode is coated with γ -APTES, acetylcellulose, Nafion®, glucose oxidase, and polydimethylsiloxane to prevent interference species is reported here. Tests of the sensor demonstrate its imperviousness to the effects of ascorbic acid ( p -acetaminophen ( y =0.935 x +0.564, n =37).

Transcutaneous lactate monitoring based on a micro-planar amperometric biosensor

Abstract A transcutaneous lactate monitoring method has been developed by combining a suction effusion fluid (SEF) collecting technique with a micro-planar amperometric biosensor. SEF is directly collected by a weak suction through the skin from which the stratum corneum has been removed. A micro-planar biosensor, has also been developed for determining lactate concentrations in very small samples. The biosensor utilizes a lactate oxidase immobilized membrane on a micro planar platinum electrode to yield a lactate sensor. The sensor is based on amperometric detection of hydrogen peroxide generated by the lactate oxidase-catalyzed oxidation of l -lactate. The linearity of the lactate sensor response was obtained from 0.5 mM to 25 mM and the response time was about 10 s. The sensor was applied to the SEF lactate measurement of a rabbit during induced high lactate levels. Lactate concentrations measured with SEF showed good correlation with those obtained directly from whole blood. This result suggests the feasibility of transcutaneous lactate monitoring without the use of blood sampling.

New transcutaneous sampling of glucose for patients with type II diabetes using an ion-sensitive field-effect transistor

Blood glucose change during the 75-g oral glucose tolerance test (g OGTT) was monitored by suction effusion fluid (SEF) sampling in five patients with type II diabetes. SEF is a small volume of fluid sampled by sucking the stratum corneum-stripped skin by an absolute pressure of 400 mmHg without bleeding or subcutaneous hemorrhage. Serum glucose and SEF glucose in each 5-μl sample were measured by an ion-sensitive field-effect transistor (ISFET) glucose sensor. The coefficients of determination between the SEF and serum glucose change were between 0.759 and 0.964, and after adjusting sampling delay they became between 0.839 and 0.996, irrespective of the patients age, diabetic history and diabetic complications. The damage to the sucked skin surface was mild with pressed mesh forms. Transcutaneous monitoring was achieved in diabetic patients with mild skin damage by the SEF sampling method.

Transcutaneous Lactate Monitoring With A Micro-planar Amperometric Biosensor

A transcutaneous lactate monitoring method has been developed by combining a suction effusion fluid (SEF) collecting technique with a micro-planar amperometric biosensor. SEF is an interstitial fluid obtained by applying suction to corneum layer-stripped skin. The micro-planar amperometric biosensor, was developed for determining lactate concentrations in very small SEF samples. The biosensor utilizes a lactate oxidase immobilized membrane on a micro-planar platinum electrode to yield a lactate sensor. Linearity in the lactate sensor output was obtained from 0.5 mM to 25 mM and the response time was about 10 seconds. The sensor was applied to measure the SEF lactate in a rabbit after a high lactate level had been induced in the animal. Lactate concentrations obtained for SEF corresponded well with those obtained directly for whole blood, suggesting the feasibility of transcutaneous lactate monitoring without the use of blood sampling.

Development of a pen-shaped scanner and its applications

A truly portable scanner would add another dimension to mobile computing. Using the compact optical configuration single optical fiber imaging (SOFI), a handheld scanner can be built inside a penshaped housing. Here, an image sensor formed on a glass substrate is used. Each photodiode of the image sensor has multiple apertures coupled to multiple optical fibers. The light is transmitted through the glass, the apertures and the fibers successively, and a document is illuminated. Scattered light comes back in the same fibers and is detected by a sensitive part of the photodiode. Therefore, a single fiber is involved to both illuminate the document and detect the reflected light. By incorporating light-absorbing material at the fiber boundaries, optical crosstalk inside the fiber array is suppressed. The design of this SOFI-based scanner is studied in detail. A prototype is developed: the width of its housing and the input length are 13 and 110 mm, respectively. The key components are an image sensor fabricated by a-Si and poly-Si thin film technology, a 2 mm-thick array of optical fibers with 0.9 numerical aperture, and an array of three-color LEDs. Images of color documents and fingerprints are successfully acquired by this scanner.