The detection of local and dynamic concentration changes of various bioactive substances in the mammalian central nervous system (CNS) is important for understanding the physiological function of excitatory synaptic transmission and metabolism. Many methods have been developed for the in vivo and in vitro detection of bioactive substances in biological fluids, including in vivo voltammetry, 1-3 patch-clamp biosensors, 4-7 microdialysis (MD) combined with various analytical methods 8 and ionselective microelectrode methods. 9 These methods have been widely used for detecting neurotransmitters, second messengers and other bioactive substances that play a key role in neuronal signal transmission.L-Glutamate is an excitatory neurotransmitter, and its release is thought to play a crucial role in brain development, synaptic plasticity, memory formation and neurotoxicity. 10 25 which is much larger than the electrodes for direct measurements, and the time resolution is on the order of minutes. In addition, the recovery of MD sampling is usually low because released L-glutamate is diluted by a perfusion solution. Niwa et al. used a glass capillary, instead of an MD probe, for sampling L-glutamate in a suction mode, followed by flow-through detection at a GluOx/Os-gel-HRP modified electrode. 26 On-line approaches using liquid chromatography, flow injection analysis and capillary electrophoresis in combination with MD probes have also been reported. 8 Improvements of the spatial dissolution of L-glutamate measurements by miniaturizing the size of sampling probe and/or that of enzyme-based electrodes are important, because the neuronal activity that releases and metabolizes L-glutamate is a very fast event, 10 and hence the concentration of Lglutamate detected at a sensing probe depends on the location and distance of the probe from the neurons. For the purpose of miniaturizing the size of the sensing probes, pulled glass capillaries 27,28 have a unique feature: the tip diameters range from submicro-to several µm, and the glass surface has an affinity to lipids and biocompatibility.In the present paper, we describe a new glass capillary microelectrode (tip diameter, ∼12 µm) based on capillarity for measuring L-glutamate. The inner solution provides a reservoir for enzymes, i.e., L-glutamate oxidase and L-ascorbate oxidase, and a built-in three-electrode system Humanities and Sciences, Nihon University, Sakurajousui, Setagaya, Japan A new glass capillary microelectrode for L-glutamate is described using pulled glass capillaries (tip size, ∼12.5 µm) with a very small volume (∼2 µl) of inner solution containing glutamate oxidase (GluOx) and ascorbate oxidase. The operation of the electrode is based on capillary action that samples L-glutamate into the inner solution. The enzyme reaction by GluOx generates hydrogen peroxide that is detected at an Os-gel-HRP polymer modified Pt electrode in a three-electrode configuration. The amperometric response behavior of the electrode was characterized in terms of the capillarity, re...

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To meet the increasing demands for the more refined semiconductor design rules and the more enhanced optical disk memory density, a very fine motion control based upon numerical control technology such as under submicron meter encoder feedback is required. The first major subject is how to keep a desired motion clear of elasticity of feeding mechanism. The second one is how to keep a load insensitive motion free from change of load and influence of disturbance. In this pa-

Takashi YAMAGIWA and Masatake SHIRAISHI This paper deals with a control structure and a method for reducing relative displacement in a three-dimensional coordinate measuring machine. In general, this system consists of a numerical controller, a servo motor, an elastic feed mechanism and a scanning mechanism. In a scanning mechanism, a tip position attached to the tool or the probe and the controlled position are usually arranged at the other positions each other, so that the relative displacement between both positions causes measuring errors. We clarify the control structure that can provide a relative displacement based on a three-inertia system and then propose a control method for reducing relative displacement. In the proposed method, current, velocity and position control loops with a damping compensator are applied to the control object modeled by the three-inertia system. The result of the control structure analysis is validated by simulation and experiments.