Fig. 6: Sensor performance with milk and blood sample tests.

The OCP for all milk and blood samples was recorded and was used to diagnose SCH through milk samples. a Shows the ionic Ca²⁺ concentration of the blood samples measured with commercial Ca-sensor. c Indicates the OCP response of the 3D-printed Ca-sensor in blood samples of both control (healthy) and subclinical hypocalcemia (SCH) groups. The Ca²⁺ and P sensors OCP signals of each sample from sensors were compared with commercial Ca– and P–meters. Results of both sensors and commercial meters are compared and their co-relation coefficients (r² = 0.95 for Ca²⁺ and r² = 0.97 for P) are estimated as shown in (b) and (d). e In the milk sample analysis, we plotted the ratio of Ca-sensor to P-sensor readings (OCPs) for each milk sample to separate healthy cows from SCH cows. This ratio in milk samples can be used to determine SCH. f The EDTA (10 mM) as masking agent spiked in the 10 milk samples of the healthy cow result in significant drop in the OCP signal. To get access of these real samples for the Virginia Tech Kentland farm, we first obtained an IACUC (Institutional Animal Care and Use Committee #24-093) approval from Virginia Tech. We have chosen Holstein cows specially those are during their postpartum transition periods. Error bars are the SD of three repeated measurements (n  =  3 biologically independent experiments). Error bars, mean ± SD. One way ANOVA have been performed and the p values were indicated. Source data are provided as a Source Data file.