Abstract: An apparatus for non-invasively estimating bio-information and a method of determining whether a bio-signal is normal by the apparatus for estimating bio-information are provided. The apparatus for estimating bio-information according to an embodiment of the disclosure includes: a photoplethysmogram (PPG) sensor configured to measure a PPG signal from an object; and a processor configured to extract a plurality of pairs of local maximum points and local minimum points from a second derivative signal of the PPG signal, to select at least one reference pair from among the extracted plurality of pairs, and to determine whether the PPG signal is normal based on the selected at least one reference pair.

Abstract: An apparatus for estimating bio-information may include: a bio-signal acquirer configured to acquire a bio-signal; and a processor configured to extract one or more first feature values from the bio-signal, determine a scale factor based on the first feature values, and to estimate bio-information based on the scale factor and the first feature values.

Abstract: A device for self-diagnosis in a present invention includes a diffusion compartment having a porous diffusion passage at either end thereof, a sensing cell installed below the diffusion compartment for generating electromotive forces depending on the oxygen concentration via two electrodes provided on the upper and lower surfaces thereof, and a pumping cell for regulating the oxygen pressure in the diffusion compartment via two electrodes installed above the diffusion compartment. Also a method for self-diagnosis in a present invention comprises the step for operating A/F sensor, comparing a measured pumping voltage, making compensations in an output signal of the A/F sensor and diagnosing the corresponding A/F sensor if the pumping voltage value exceeds upper-limit voltage.