A diagnostic device 10 for screening for a target analyte in a sample is provided. The diagnostic device 10 comprises a substrate 12 and a hydrophobic material 20 disposed on the substrate. The hydrophobic material 20 is selected to be converted from the hydrophobic material 20 to a hydrophilic material 22 upon contact with a conversion component within or derived from a sample introduced to the device 10.

A method of calibrating a device for measuring the concentration of creatinine in a sample including one or more enzyme modulators, the device comprising an enzyme layer, the method comprising: determining sensitivities of the device for each of one or more calibration solutions; determining a degree of modulation for the sample to be measured, determining a degree of modulation for each calibration solution; wherein said determining of each of the degrees of modulation comprises estimating the concentration of an enzyme modulator in the enzyme layer of the device; and calculating the sensitivity of the device for the sample, wherein the said calculating comprises adjusting the sensitivity of the device for each calibration solution by a factor comprising the determined degrees of modulation of the sample and the calibration solution.

Creatinine levels may be monitored as a measure of kidney function. Conventionally, blood and/or urine tests are used for this purpose. Analyte sensors capable of monitoring creatinine in vivo may comprise: a sensor tail comprising at least a first working electrode, a creatinine-responsive active area disposed upon a surface of the first working electrode, a first membrane that is permeable to creatinine and overcoats the creatinine-responsive active area, and an oxygen scavenger located upon the sensor tail in proximity to the creatinine-responsive active area. The creatinine-responsive active area comprises a first electron transfer agent, a first polymer, and an enzyme system comprising multiple enzymes, particularly creatinine amidohydrolase, creatine amidohydrolase, and sarcosine oxidase, that are capable of acting in concert to facilitate detection of creatinine. An oxidase enzyme may serve as the oxygen scavenger, particularly glucose oxidase when detecting creatinine in fluids also containing glucose.

A diagnostic device 10 for screening for a target analyte in a sample is provided. The diagnostic device 10 comprises a substrate 12 and a hydrophobic material 20 disposed on the substrate. The hydrophobic material 20 is selected to be converted from the hydrophobic material 20 to a hydrophilic material 22 upon contact with a conversion component within or derived from a sample introduced to the device 10.

A method of calibrating a device for measuring the concentration of creatinine in a sample including one or more enzyme modulators, the device comprising an enzyme layer, the method comprising: determining sensitivities of the device for each of one or more calibration solutions; determining a degree of modulation for the sample to be measured, determining a degree of modulation for each calibration solution; wherein said determining of each of the degrees of modulation comprises estimating the concentration of an enzyme modulator in the enzyme layer of the device; and calculating the sensitivity of the device for the sample, wherein the said calculating comprises adjusting the sensitivity of the device for each calibration solution by a factor comprising the determined degrees of modulation of the sample and the calibration solution.