P3HT and PEDOT:PSS printed thin films on chemiresistors: An economic and versatile tool for ammonia and humidity monitoring applications

Abstract

We hereby present the fabrication of simple and efficient humidity and ammonia sensors based on a chemiresistor design employing a differential measurement technique. Interdigitated electrodes are connected via PEDOT:PSS or P3HT polymers and a reproducible and scalable fabrication procedure is presented. This procedure utilizes pneumatic nozzle printing instead of drop or spin-based processes and includes an optimized encapsulation procedure and material for sealing the reference electrodes. The suitability of the NH 3 sensor for quantifying ammonia in a range of 2 to 100 ppm within a period of several months is furthermore presented. The developed humidity sensor is operational for several months in a humidity range between 10 and 60% RH. Once this range is exceeded, a sensor decay by irreversible saturation can be observed. Based on the low fabrication costs of the sensors ($0.5 $ when ordering 1000 pcs of the platform + printing work), they provide a very attractive tool for industrial humidity and ammonia sensing applications.

Conductive Molecularly Imprinted Polymers (cMIPs): Rising and Versatile Key Elements in Chemical Sensing

“…[147] Based on remarkable progress on the hardware site within the last 10 years, e.g., the widespread use of smartphone apps or the possibility for large-scale data monitoring (10-100 km radius) using open access networks, which neither requires a phone or service contract [148], a strongly increasing demand for accurate and stable sensors can be expected. This could be solved by, e.g., Universal Serial Bus (USB, or USB C)-based sensing platforms, which can be easily coupled with the digital world [75]. Simple sensing concepts, such as, e.g., chemiresistors in combination with cMIPs, therefore bear a huge potential to be tailored for a wide range of practical applications based on their sensing layer.…”

“…Another challenge faced by PEDOT-based sensing layers in particular is the polymers' high hygroscopicity. Swelling and collapsing upon fluctuations in ambient humidity result in significant alterations of the polymers' electric conductivity unrelated to specific analyte interactions [75]. In order to reduce such humidity-induced changes, hydrophobic additives can be included in the imprinting protocol [76].…”

Flexible and Printed Chemiresistive Ammonia Gas Sensors Based on Carbon Nanotube and Conjugated Polymers: A Comparison of Response and Recovery Performance

“…Additionally, during the 1 h of recovery, an increase in resistance was observed, resulting in an upwards drift of the sensor. Kumpf et al found similar values for their P3HT-based sensor and further reported that low concentrations of P3HT (<5 mg/ml in toluene) have the tendency to reach cut-off value of 50 M overtime, resulting in a loss of conducting ability [21]. At low concentrations of ammonia (5 ppm), a fluctuation in resistance (noise) made it difficult to accurately calculate the control P3HT sensor performance.…”