Department of Biomechatronics Engineering, National Taiwan University
Tomatake Hall 403
Research topics
1. Multi-ion Monitoring System for Automatic Nutrient Solution Regulation and Crop Quality Management:
Using the intelligent high-throughput ion sensing system and the core technology of solid-state ion sensing electrode array, combined with multi-channel potential sensing modules and wireless transmission devices, the system enables rapid and simultaneous measurement of various ion concentrations in water bodies. This achieves real-time remote monitoring and long-term tracking. Since ions are the main source of plant nutrition, monitoring the ion concentrations in soil or hydroponic nutrient solutions indicates whether the nutritional supply for plants is sufficient and balanced. Regularly obtaining quantitative data allows for more precise crop cultivation management. Additionally, ions also reflect the health status of plants and can be used to define and track quality and yield.
The system can measure seven ion concentrations, including nitrate, ammonium, potassium, calcium, magnesium, sodium, and chloride ions, as well as pH value. The linear measurement range for concentrations is 0.1 M to 0.1 mM, with a detection limit of 0.01 mM. The system is equipped with an automatic control device that can automatically replenish missing ions based on sensor data. It is compact, lightweight, and suitable for different field applications.
Furthermore, for examining plant physiological needs, the system can measure plant sap on-site without the need for filtration or additional reagents. This provides real-time feedback on crop physiological conditions for more precise cultivation control. The data can also be stored in a database for quality prediction purposes.
Figure 1. Multi-ion monitoring system
Metal-organic frameworks (MOFs) are catalytically active materials that can be applied in the sensing of organic molecules. To create electrochemical sensors using MOFs, the immobilization method on the electrode surface is a crucial consideration. In this study, a encapsulation technique was employed to electrodeposit conductive polymers with MOF818 or MOF199 onto the electrode surface, forming a sensing film. The conductive polymer film serves as a substrate for encapsulating the metal-organic framework, facilitating electron signal conduction.
The PEDOT film embedded with MOF199 was applied in a voltammetric caffeine sensor, with a measurement range of 1 to 3 mM (typical caffeine concentration in coffee). The sensitivity was determined to be 0.246 mA/cm^2/mM. Additionally, a voltammetric chlorate sensor was developed using the PEDOT film embedded with MOF818. This sensor exhibited Michaelis-Menten kinetics, where the reciprocal of current is a linear function of the reciprocal of concentration, with a Michaelis constant of 1.4 mM. Both sensors demonstrated significant selectivity for the target molecules (relative to ascorbic acid, glucose, sucrose, vanillin, theophylline, and phenol). These results indicate the promising potential of this system.
2. Application of Encapsulated Metal-Organic Frameworks in Conductive Polymers for Molecular Sensing:
Figure 2. Application of metal-organic framworks in E-tougue
3.Real-time Impedance-Based Aptasensing Platform Utilizing Microfluidic Systems:
This study developed a microfluidic system for an aptasensing platform, adopting a fork-shaped electrode combined with electrochemical impedance methods to monitor the real-time binding of targets and aptamers for quantitative analysis. This approach allows the estimation of the kinetic parameters of the aptamer. The use of fork-shaped electrodes, known for their ease of miniaturization, manufacturing, and modification, expands the applicability of electrochemical sensors. However, in a two-electrode system, the semi-infinite diffusion phenomenon leads to unstable output currents, limiting sensitivity, specificity, and detection limits. Therefore, this study developed a microfluidic fork-shaped electrode array platform, optimizing fluidic parameters to confine the electrochemical reaction within the near-diffusion layer. This improvement increases the reaction rate, aiding in amplifying the desired oxidative-reductive cycle signals for detection. Through this platform, the binding rate constant (kon) and dissociation rate constant (koff) of the aptamer can be solved. Consequently, new affinity measurement strategies can be validated, and the practical application potential of biosensors can be confirmed.
Figure 3. Real-time impedance-based aptasening platform