To design and develop a polymer-based sensor for detecting ethanol in water, we will follow these steps:1. Selection of polymer: Choose a polymer that has a high affinity for ethanol and is stable in water. One such polymer is polyvinyl alcohol PVA , which is known for its hydrophilic properties and good film-forming ability. PVA can be crosslinked to improve its stability and selectivity towards ethanol.2. Sensor fabrication: Prepare a thin film of PVA by dissolving it in water and casting it onto a glass substrate. Crosslink the PVA film using a suitable crosslinking agent, such as glutaraldehyde, to enhance its stability and selectivity towards ethanol. The crosslinked PVA film will serve as the sensing layer of the sensor.3. Sensor transduction mechanism: To convert the interaction between the sensing layer and ethanol into a measurable signal, we can use optical or electrical transduction mechanisms. For example, we can monitor the change in the refractive index of the PVA film upon ethanol absorption using an optical fiber-based setup or measure the change in the electrical resistance of the film using interdigitated electrodes.4. Sensor calibration: Expose the sensor to different concentrations of ethanol in water ranging from 0 to 50 mg/L and record the corresponding changes in the optical or electrical signal. Plot the sensor response as a function of ethanol concentration and establish a calibration curve.5. Sensor evaluation: Assess the performance of the PVA-based sensor in terms of sensitivity, selectivity, response time, and stability.- Sensitivity: Calculate the slope of the calibration curve to determine the sensitivity of the sensor. A higher slope indicates better sensitivity.- Selectivity: Test the sensor's response to other common water contaminants, such as methanol, acetone, and isopropanol, to evaluate its selectivity towards ethanol. A highly selective sensor will show minimal response to these interfering substances.- Response time: Measure the time taken by the sensor to reach a stable response upon exposure to ethanol. A shorter response time indicates faster detection.- Stability: Assess the sensor's stability by monitoring its response over multiple cycles of ethanol exposure and recovery. A stable sensor will maintain its sensitivity and selectivity over time.6. Comparison with existing sensors: Compare the performance of the PVA-based sensor with other existing ethanol sensors, such as those based on metal-oxide semiconductors, conducting polymers, or enzyme-based systems. Consider factors like sensitivity, selectivity, response time, and stability to determine the advantages and limitations of the PVA-based sensor.By following these steps, we can design and develop a polymer-based sensor for detecting ethanol in water and evaluate its performance in comparison to other existing sensors.