Fabrication and package of ISFET biosensor for micro volume analysis with the use of direct ink writing approach

The present paper suggests a universal foundation for fabrication of biosensor microsystems based on ion-sensitive field effect transistor (ISFET). Combination of complementary metal-oxide-semiconductor (CMOS)-technological solutions and direct ink writing (DIW) technology for creation of the sealed microfluidic system able to deliver the reagents to sensitive ISFET surface is the key feature of the work. The ISFET plays role of a signal transducer with sensitive surface that can be modified with different receptive layers consisting of enzymes, or aptamers, or antibodies. DIW method is used as variation of sacrificial layer technique. 3D scaffold formed of viscoelastic ink is used as the sacrificial layer; epoxy resin works as sealant. Enzymatic biosensors for the determination of c and organophosphate pesticides were developed as a proof of concept. Limit of detection (LOD) for trinitrotoluene (TNT) and paraoxon molecules was estimated as 5 ppb and 30 ppb respectively.