In this paper, urea biosensors based on detection of pH and ammonium ions are presented. As transducers pH-sensitive ion-selective field effect transistors (ISFETs) and chemically modified FETs (ChemFETs) sensitive to ammonium ions were used. Results concerning urea determination by the biosensors in blood plasma and in dialysate show that the biosensors can be applied for urea monitoring in th...

Biologically sensitive field-effect transistors (BioFETs) are one of the most abundant classes of electronic sensors for biomolecular detection. Most of the time these sensors are realized as classical ion-sensitive field-effect transistors (ISFETs) having non-metallized gate dielectrics facing an electrolyte solution. In ISFETs, a semiconductor material is used as the active transducer element...

Accurate measurements of soil macronutrients (i.e., nitrogen, phosphorus, and potassium) are needed for efficient agricultural production, including site-specific crop management (SSCM), where fertilizer nutrient application rates are adjusted spatially based on local requirements. Rapid, non-destructive quantification of soil properties, including nutrient levels, has been possible with optica...

was readily constructed by simple modification of a common FID hydrocarbon monitor, with addition of a commercially available valve oven, switching valve, and timer. This system, except for the adjusted response time, had virtually the same operating specifications as the original hydrocarbon analyzer. Short-term studies indicated the system was practical, reliable, and accurate. Air-monitoring...

The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summariz...

A Wireless Sensor Networks (WSN) is now widely used in precision agriculture applications. Sensors play an important role in WSN. The measurement of soil pH is arguably the most widely performed test in the chemical laboratory, the use of pH sensitive field-effect transistors (pHFETS) is proposed for remote monitoring of the nutrient solution composition for an agricultural farm soil. The propo...