Stimuli-sensitive or responsive (smart) hydrogels, or chemofluidic transistors, are the base of the key control elements of smart chemomechanical valves. These valves have an outstanding potential for miniaturized, integrated sensor and actuator systems in many application areas and especially for lab-on-chip technology. Due to the multifaceted design parameters the design and realization of hydrogel-based systems are exceptionally complex and demanding.
In this work we compare two types of stimuli-sensitive hydrogel-based valves with two types of electronic transistors and analyze analogies. As a result, the membrane isolated chemical volume phase transition Transistors (MIS-CVPT’s) exhibit a behavior with various analogies to electrical Field Effect Transistors (FET’s). The FET device embodies a voltage-controlled channel resistor, which is related to the chemically controlled fluidic channel of the MIS-CVPT. Chemical volume phase transition transistors (CVPT’s) on the other hand show in part similarities both to the bipolar transistor (BJT) and the MOSFET. The analogies allow a closed description of a microfluidic system by equivalent circuits and an efficient behavioral simulation by sophisticated circuit simulators.
Several chemofluidic circuits, as a microfluidic oscillator, a NAND gate and an Analog/Digital Converter (ADC) and their behavioral simulation will be presented. The applied lab-on-a-chip (LoC) predictive simulation-based design concept is very helpful as it saves many practical experiments and leads to optimized components.