The review paper explains a short history of development of a taste sensor, which was first developed in Japan and can measure taste of foods and pharmaceuticals. The patent of taste sensor using lipid/polymer membranes was applied in 1989, and the first Taste Sensing System was developed and put on market in 1993. The taste sensor developed during the first 15 years had the property to show cross-selectivity to taste qualities and hence the pattern from outputs of several sensor electrodes was treated to estimate taste. A taste sensor developed around 2007 has the property of global selectivity which means that the sensor can classify the taste to five basic taste qualities and quantify the taste because each sensor electrode responds selectively to each of taste qualities. Lipid/polymer membranes of the taste sensor provide a good example of soft materials with functional surface.

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Many drugs elicit a bitter taste, so development of a method to mask bitterness is widely required in pharmaceutical sciences. The human sense of taste is subject to both physiological properties and individual preferences, and a general approach, which is also applicable to the paediatric population, is not yet available. The toxicity of new chemical entities plays a major role in early preclinical development and may lead to limitations with respect to taste assessment. Therefore, taste sensor may offer an objective and safe method for comparing different formulations with respect to taste masking. The bitterness intensities of pharmaceutical ingredients were evaluated using taste sensor. We introduce two studies, evaluation of bitterness intensity of active pharmaceutical ingredients and pharmaceutical preparation including bitter-taste active pharmaceutical ingredient.

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The review paper explains a short history and a current state of development of sweetness sensors in the taste-sensing system, which is the first commercialized taste sensor in the world. Since the first commercial SA401 Taste Sensing System was released in 1993, the sweetness sensor has been one of the most difficult problems on the development of the taste sensor. This is because nobody can explain the common and unique characteristics of sweet substances. It is difficult to realize the global selectivity for sweetness. “Global selectivity” means the consistency of response to the same taste similar to the human tongue, despite the various chemical structures and sizes of tastants. Hence, we decided to develop three different sweetness sensors, that is, for positively, negatively and noncharged sweeteners. The developed three sweetness sensors have high selectivity. In the near future, they will contribute to the development of the low-calorie diet and the pharmaceutical products whose bitterness was masked by high-potency sweeteners.

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Food ingredients' tastes were measured by a taste sensor and a optimization problem for food ingredients and their blend ratios was solved using a genetic algorithm(GA) to fit the food taste vector to a target taste one. First, the tastes of food ingredients were measured by a taste sensor. Next, chromosomes used by GA were set using genes defined by the serial numbers on the ingredients. Third, the problem was reduced to blend ratio optimization problems for the ingredients with the serial numbers given by the chromosomes, and the reduced problems were solved to fit the food taste vector to a target taste one. Using the fitness function of the chromosome defined by the taste error of the reduced problem, the chromosomes were improved using GA. Approximate sparse solutions of the taste optimization problem for more than thousand food ingredients were thus derived. Using this algorithm, optimum food ingredients and their blend ratios were obtained for a target taste vector.

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According to the results of a questionnaire in the Program for International Student Assessment (PISA) conducted in 2006 by the Organization for Economic Co-operation and Development (OECD), high school students in Japan don't realize the interest and usefulness of learning science. Many events on science education targeting high school students have been held in an attempt to solve this problem. The purpose of this study is to develop a simple fabricated taste sensor with sensitivity and selectivity which can be applied in science class using filter paper and lipid solutions. The fabricated taste sensor with lipid membranes composed of trioctylmethylammonium chloride (TOMA) and phosphoric acid di(2-ethylhexyl) ester (PAEE) showed a good selectivity for sodium chloride (saltiness) and citric acid (sourness), respectively. In a sensory test, the results of sensors correspond to the sensory score. Thus, it was indicated that the fabricated taste sensor for education is a useful science teaching material.

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In this paper, business application of the Taste Sensing System is described. Development races of private label brands are heating up in the domestic food industry. It is because consumer needs are diversifying year by year and need to respond them to survive in the market. Thorough pursuit of consumer needs is crucial in product developments. A taste sensor can visualize the needs into numerical data. As a result, a concept of product development becomes clear and therefore its target values are clarified. Besides that, cost reduction and a reduction in the number of raw materials can be possible by applying a mathematical optimization based on a database of sensor outputs. Effective appealing to buyers and consumers is realized by showing characteristics of a new product or renewal product in digitized taste data. In the global market, taste preferences depending on regions are not easy to understand and communicate with each other through their own languages. To understand the differences, a common taste measure is required. By using the measure of taste, it is possible to make smooth communication between producers of farm products and food manufactures.

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Approximately 310,000 visually impaired people are currently living in Japan. For the people, going outside is a risky task. In fact, it is often reported that they fall from a platform or stairs. In order to prevent such accidents, it is possible to develop a system for navigating around obstacles including platform and stairs using GPS. However, GPS cannot be used indoors. This paper presents a system of detecting an indoor staircase leading downward. The proposed system combines the Hough transform and a phase-only correlation method to increase the performance of the system. The proposed system is composed of a common camera and a common laser-pointer. Experiments show that the proposed method achieved 96.6% accuracy within 0.2∼0.7 seconds computation time.

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This paper reports mathematical modeling method of MEMS micro heater and analysis method of dynamic characteristics of the temperature controller for the micro heater. The model expressed by the main heat transfer phenomenon in the heater system shows the response properties similar to actual device. Moreover, the temperature controller IC designed using the model shows characteristics similar to simulation. By this technique, we can improve the development efficiency of temperature controller for sensors with the micro heater.

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