Smart diaper for detecting and differentiating feces and urine

A method of monitoring a diaper using a diaper sensor, the method comprising:

• detecting, at a control circuit of a diaper sensor, that a dissolvable resistor has dissolved;
• measuring a conductivity between a pair of conductive elements in a diaper;
• determining, at the control circuit, a presence of feces or urine based on the measurement of conductivity;
• and
• causing a transmitter to transmit a signal indicative of the presence.

A diaper sensor for differentiating feces and urine in a diaper, comprising:

• a pair of conductive elements positioned within an absorbent region of a diaper;
• a power source;
• a transmitter;
• a dissolvable resistor;
• a control circuit operatively connected to the conductive elements that are positioned with an absorbent region of a diaper and to the transmitter,
• wherein the control circuit is configured to perform operations comprising:
• detecting that the dissolvable resistor has dissolved;
• measuring a conductivity between the conductive elements;
• determining a presence of moisture based on the conductivity;
• causing the power source to apply a signal at a particular frequency to the pair of conductive elements;
• measuring a conductivity between the pair of conductive elements to determine an impedance;
• determining, based on the impedance being greater than a first threshold but less than a second threshold, that feces are present in the diaper, wherein the first and second thresholds are determined based on the particular frequency of the signal;
• and
• transmitting via the transmitter a signal indicative of whether feces or urine is present in the diaper.