How do glucometers work?
The glucometer works on the well-established principle of amperometry, where the peak current obtained during an electrochemical reaction, maintaining a constant potential between the electrodes, is taken as an indicator of the concentration of the analyte.1
A typical amperometric sensor consists of three electrodes – the working (WE), reference (RE) and counter electrodes (CE). Glucometer test strips commercially available today are enzymatic electrochemical biosensors, which are disposable.
How do oximeters work?
The oximeter emits red and infra-red light through the fingertips and a sensor detects the amount of light the blood absorbs. Normal oxygenated blood absorbs more infra-red light rather than red light, giving a high oxygen saturation percentage.2 Heart rate can also be detected through the oximeter by measuring the change in light absorption (and hence, oxygen levels) over time.
1 Mohan, Madhu & E, Anoop & Guruvayurappan, Krishnan. (2014). Simulation of a Multi-Strip Blood Glucometer. IEEE Region 10 Annual International Conference, Proceedings/TENCON. 2015. 10.1109/TENCON.2014.7022473.
2 Chan, E.D., Chan, M.M. and Chan, M.M., 2013. Pulse oximetry: understanding its basic principles facilitates appreciation of its limitations. Respiratory medicine, 107(6), pp.789-799.