Sensors are affordable and easy-to-use devices for trace level monitoring of various ions. Among the various types of sensor, carbon paste (CPE) and screen printed (SPE) electrodes are the most applicable for biosensor and chemical sensor applications, due to their cost-effectiveness and ease of preparation and modification. This is in addition to the excellent mechanical properties of the electrode surface, good stability and reproducibility of the electrode response, and long lifetime. In addition to the importance of the sensor type, the sensing electroactive material used for the sensor modification is also of significant importance as it plays a key role in determining the selectivity and sensitivity of the established sensor. Nevertheless, there are various types of sensing materials that have been utilised, but for some applications their detection levels are restricted. On the other hand, nanoscale materials represent a new class of electroactive materials due to their unique properties, such as their high surface areas. Hence, the incorporation of nanoscale materials into electrode designs will achieve a high detection limit for the analyte.

Significant attempts have been devoted to developing environmentally friendly and cost-effective sensors for the trace level detection of important ions, from both chemical and biological perspectives. This may be attributed to several attractive features, such as portability, economical instrumentation, and the ability to perform measurements in turbid samples. On this account, it is necessary to establish new trends in these sensors based on the precise utilisation of zero, one, and two-dimensional nanomaterials and new hybrid porous metal-organic frameworks for multiple applications, such as medical diagnostics, and food, pharmaceutical, and environmental monitoring.

The aim of this Special Issue is to open new venues for researchers to present new trends in the environmentally friendly and cost-effective fabrication of functionalised biological and chemical nanomaterial-based sensors, for the precise detection of various analytes. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Metal organic framework-based potentiometric sensors for trace level ion detection
• Nanomaterial-based ion selective electrodes
• Different carbon form-based sensors for pharmaceutical monitoring
• Selective voltametric sensors for metal ion detection
• Green synthesised and cost-effective electroactive materials for promising biosensor fabrication