Abstract: Embodiments of the inventive concept include a portable ion concentration apparatus including a controller, a storage section to store one or more data samples, an amplifier circuit, and a chemical field effect transistor (CHEMFET). The CHEMFET and the amplifier circuit can indicate a quantity of nitrate levels in a sample media or a reference media. The controller can process the indication of the quantity of nitrate levels, and generate the one or more data samples based at least on the indication of the quantity of nitrate levels. The portable ion concentration apparatus can include an in-field analysis apparatus, an in-field measurement apparatus, or an in-soil monitoring apparatus. A measurement logic section can determine an ion concentration based on a sensitivity slope M or a polynomial fit. Also disclosed is a method for measuring ion concentration with a standard deviation correction.

Abstract: Embodiments of the inventive concept include a portable ion concentration apparatus including a controller, a storage section to store one or more data samples, an amplifier circuit, and a chemical field effect transistor (CHEMFET). The CHEMFET and the amplifier circuit can indicate a quantity of nitrate levels in a sample media or a reference media. The controller can process the indication of the quantity of nitrate levels, and generate the one or more data samples based at least on the indication of the quantity of nitrate levels. The portable ion concentration apparatus can include an in-field analysis apparatus, an in-field measurement apparatus, or an in-soil monitoring apparatus. A measurement logic section can determine an ion concentration based on a sensitivity slope M or a polynomial fit. Also disclosed is a method for measuring ion concentration with a standard deviation correction.

Abstract: Embodiments include a method for securing a membrane material to a gate of a molecular receptor-based chemical field-effect transistor (CHEMFET). The method can include casting a membrane material onto an exposed region of the gate, curing the membrane material, placing the CHEMFET into a mold, inserting a single application of impervious electrically insulative resin into the mold, and securing edges of the membrane material by the single application of the impervious electrically insulative resin, thereby physically preventing lifting off of the membrane material from the gate. Embodiments include a sensor module. The sensor module can include a CHEMFET, an amplifier circuit, one or more sensor pins for contacting field ground soil, a data logger, and a wireless transceiver, among other components.

Abstract: Embodiments of the inventive concept include a portable ion concentration apparatus including a controller, a storage section to store one or more data samples, an amplifier circuit, and a chemical field effect transistor (CHEMFET). The CHEMFET and the amplifier circuit can indicate a quantity of nitrate levels in a sample media or a reference media. The controller can process the indication of the quantity of nitrate levels, and generate the one or more data samples based at least on the indication of the quantity of nitrate levels. The portable ion concentration apparatus can include an in-field analysis apparatus, an in-field measurement apparatus, or an in-soil monitoring apparatus. A measurement logic section can determine an ion concentration based on a sensitivity slope M or a polynomial fit. Also disclosed is a method for measuring ion concentration with a standard deviation correction.

Abstract: Embodiments include a method for securing a membrane material to a gate of a molecular receptor-based chemical field-effect transistor (CHEMFET). The method can include casting a membrane material onto an exposed region of the gate, curing the membrane material, placing the CHEMFET into a mold, inserting a single application of impervious electrically insulative resin into the mold, and securing edges of the membrane material by the single application of the impervious electrically insulative resin, thereby physically preventing lifting off of the membrane material from the gate. Embodiments include a sensor module. The sensor module can include a CHEMFET, an amplifier circuit, one or more sensor pins for contacting field ground soil, a data logger, and a wireless transceiver, among other components.

Abstract: Embodiments include a method for securing a membrane material to a gate of a molecular receptor-based chemical field-effect transistor (CHEMFET). The method can include casting a membrane material onto an exposed region of the gate, curing the membrane material, placing the CHEMFET into a mold, inserting a single application of impervious electrically insulative resin into the mold, and securing edges of the membrane material by the single application of the impervious electrically insulative resin, thereby physically preventing lifting off of the membrane material from the gate. Embodiments include a sensor module. The sensor module can include a CHEMFET, an amplifier circuit, one or more sensor pins for contacting field ground soil, a data logger, and a wireless transceiver, among other components.

Abstract: Embodiments include a method for securing a membrane material to a gate of a molecular receptor-based chemical field-effect transistor (CHEMFET). The method can include casting a membrane material onto an exposed region of the gate, curing the membrane material, placing the CHEMFET into a mold, inserting a single application of impervious electrically insulative resin into the mold, and securing edges of the membrane material by the single application of the impervious electrically insulative resin, thereby physically preventing lifting off of the membrane material from the gate. Embodiments include a sensor module. The sensor module can include a CHEMFET, an amplifier circuit, one or more sensor pins for contacting field ground soil, a data logger, and a wireless transceiver, among other components.