Abstract: We disclose herein a fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising a semiconductor substrate comprising a first etched portion, a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate, a heating element located within the first dielectric membrane, and a first temperature sensing element spatially separated from the heating element. The fluid sensor further comprises a second temperature sensing element within the dielectric membrane, or the heating element may be further configured to operate as a second temperature sensing element.

Abstract: A fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising: a semiconductor substrate comprising a first etched portion and a second etched portion; a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate, and a second dielectric membrane located over the second etched portion of the semiconductor substrate; two temperature sensing elements on or within the first dielectric membrane and two temperature sensing elements on or within the second dielectric membrane; an output circuit configured to measure a differential signal between the two temperature sensing elements of the first dielectric membrane and the two temperature sensing elements of the second dielectric membrane; wherein the first dielectric membrane is exposed to the fluid and the second dielectric membrane is isolated from the fluid.

Abstract: A fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising: a semiconductor substrate comprising a first etched portion and a second etched portion; a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate, and a second dielectric membrane located over the second etched portion of the semiconductor substrate; two temperature sensing elements on or within the first dielectric membrane and two temperature sensing elements on or within the second dielectric membrane; an output circuit configured to measure a differential signal between the two temperature sensing elements of the first dielectric membrane and the two temperature sensing elements of the second dielectric membrane; wherein the first dielectric membrane is exposed to the fluid and the second dielectric membrane is isolated from the fluid.

Abstract: A battery charger measures an average battery temperature at a pre-determined timing for a first fixed period after start of charging. If the number of consecutive positive second derivatives of battery temperature is four, charging is discontinued. If the number of consecutive positive second derivatives of battery temperature is not four, the charging is carried out continuously for a pre-determined secondary period.