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Development of hydrogel-based mems piezoresistive sensors for detection of solution PH and glucose concentration

The measurements for different solutions having pH values between 1 to 11 and glucose concentrations between 2.5 mM and 15 mM have been carried out. The output characteristics of sensors have been demonstrated showing the long-term reproduction and relatively good sensitivity, namely approximately 20 mV/pH for pH sensor and 7 mV/1 mM of glucose concentration for glucose sensor. | Vietnam Journal of Mechanics, VAST, Vol. 34, No. 4 (2012), pp. 281 – 288 DEVELOPMENT OF HYDROGEL-BASED MEMS PIEZORESISTIVE SENSORS FOR DETECTION OF SOLUTION PH AND GLUCOSE CONCENTRATION Trinh Quang Thong1 , Margarita Guenther2 , Gerald Gerlach2 1 Hanoi University of Science and Technology, Vietnam 2 Dresden Technical University, Germany Abstract. Hydrogels are water-swollen polymeric materials that maintain a distinct three-dimensional structure. Manipulation of hydrogel structure has produced stimulisensitive hydrogels, which change their swelling degree or undergo phase transition in response to minimal changes in environmental conditions. This paper presents the development of hydrogel-based sensors for measurement of solution pH and glucose concentration using commercial MEMS piezoresistive pressure transducers. pH-sensitive PVA/PAA and glucose-sensitive AAm/3-APB/BIS hydrogels are used in the experiments. Two types of sensor packaging, one is used as solution container and the other used to dip into solution have been performed. The measurements for different solutions having pH values between 1 to 11 and glucose concentrations between 2.5 mM and 15 mM have been carried out. The output characteristics of sensors have been demonstrated showing the long-term reproduction and relatively good sensitivity, namely approximately 20 mV/pH for pH sensor and 7 mV/1 mM of glucose concentration for glucose sensor. Keyword: Chemical sensors, MEMS piezoresistive senors, polymer hydrogels. 1. INTRODUCTION Over the years, the field of chemical and bio-sensing has evolved from simple and bulk systems to more reliable, robust and low cost microscale systems that can perform complex operations minimizing human efforts and attaining highly accurate results. These Microelectromechanical Systems (MEMS) based sensors have not only been used in industrial and automobile sectors but also have a rapid growth in the field of medical diagnostics [1]. pH is one of the most important .