Abstract: We use the AC Hall effect to characterize a magnetic field at an unknown frequency (or frequencies). The current to the Hall sensor is driven at a known frequency f. The output Hall voltage is characterized in a frequency range from f1 to f2 (with f<f1<f2 and f2?f1<2f). This provides a measurement of the magnetic field in a frequency range from f1?f to f2?f. The resulting measurement of magnetic field spectral components is phase-independent and requires no prior knowledge of exact magnetic field frequency.

Abstract: Improved magnetic field sensing is provided by switching between a Hall effect mode and an inductive mode. The inductive mode is used when the frequency of the magnetic field being sensed is above a frequency threshold. The Hall effect mode is used when the frequency of the magnetic field is below the frequency threshold. The sensor element can be any Hall effect sensor element. In the Hall effect mode, the sensor element is used conventionally, optionally including refinements such as current spinning for more accurate results. In the inductive mode, no current is provided to the sensor element. The resulting transverse sensor voltage is induced by time-variation of the magnetic field, and can be used as a measure of magnetic field strength.

Abstract: We use the AC Hall effect to characterize a magnetic field at an unknown frequency (or frequencies). The current to the Hall sensor is driven at a known frequency f. The output Hall voltage is characterized in a frequency range from f1 to f2 (with f<f1<f2 and f2?f1<2f). This provides a measurement of the magnetic field in a frequency range from f1?f to f2?f. The resulting measurement of magnetic field spectral components is phase-independent and requires no prior knowledge of exact magnetic field frequency.

Abstract: A sensor for gas species in water includes two membranes separating first, second and third chambers. The first and second chambers are separated by an ion exchange membrane, and the second and third chambers are separated by a gas permeable membrane. Water electrolysis in the first and second chambers provides analyte-ions corresponding to an analyte being detected that pass through the ion exchange membrane from the first chamber to the second chamber. Within the second chamber, these analyte-ions generate analyte via the electrolysis. Analyte in the second chamber passes through the gas permeable membrane to arrive at the third chamber. Within the third chamber, the analyte-ion is generated chemically from the analyte. Electrical detection of the analyte-ion in the third chamber provides sensing of the analyte present in the first chamber.