title: Application of ISFETs in closed-loop systems for greenhouses.
abstract: In horticulture, growing in artificial substrates such as rockwool is more and more considered to be a sound alternative to growing in soil.  This development enables the opportunity to create closed-loop systems which lower the waste of raw materials and reduce pollution of the environment.  Applying closed-loop systems needs precise knowledge of the composition of the recirculating nutrient solution.  This paper presents basic principles of a measuring system, which can monitor continuously the concentration of nutrients in water.  The system is based on ion-selective field effect transistors (ISFETs).  By appropriate calibration, a high accuracy is achieved for pH and potassium measurements in the nutrient solution.  An accuracy of better than 10% (mMol/l) has been achieved.
authors.affiliation: IMAG-DLO, Wageningen, The Netherlands.
authors.lastname: Gieling ThH
authors.forename: H H
authors.initials: HH
authors.lastname: van den Vlekkert
mesh_terms: D000383:Agriculture / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D018504:Ecological Systems, Closed; D004780:Environment, Controlled; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005308:Fertilizers / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D017736:Ion-Selective Electrodes; D007476:Ionophores; D018551:Solanum lycopersicum; D011188:Potassium / Q000032:analysis; D014867:Water / Q000737:chemistry
chemical_list: D003470:Culture Media; D005308:Fertilizers; D007476:Ionophores; D014867:Water; D011188:Potassium