Abstract: An apparatus for particulate matter (PM) measurement includes a first light source to generate a first light beam and a second light source disposed at a first distance from the first light source to generate a second light beam in parallel to the first light beam to illuminate a PM. The apparatus further includes a first light detector to measure a first timing corresponding to a first self-mixing signal resulting from a reflection and/or back-scattering of the first light beam from a PM, and a second light detector to measure a second timing corresponding to a second self-mixing signal resulting from a reflection and/or back-scattering of the second light beam from the PM. A processor can determine a first velocity of the PM based on a spatial separation between centers of the first light beam and the second light beam and a temporal separation between the first timing and the second timing.

Abstract: A portable communication device includes a transducer enclosed in an enclosure. An opening allows flow of air between the transducer enclosed in the enclosure and a surrounding environment. The enclosure protects the transducer from misreading due to occlusion of environmental aggressors on the transducer. The enclosure is configured to repel the environmental aggressors away from a surface of the transducer and to keep a portion of the opening unclogged to maintain an air flow to the transducer.

Abstract: A portable communication device may include a gas sensor enclosed in an enclosure, a port to allow flow of air into and out of the enclosure, and a light source disposed on an internal surface of the enclosure. The light source is operable to facilitate generation of ozone gas within the enclosure. The enclosure may contain a heating element that allows baseline calibration of the gas sensor by thermally decomposing ozone gas molecules. The gas sensor includes a miniature gas sensor such as a metal-oxide (MOX) gas sensor.

Abstract: A portable communication device includes a first gas sensor, one or more second gas sensors, at least one port and a calibration module. The first gas sensor is disposed on a first hotplate and is enclosed in an enclosure. The one or more second gas sensors are disposed on one or more second hotplates and are also enclosed in the enclosure. The ports can allow flow of air into and out of the enclosure. The second gas sensors are stable gas sensors, which are used by the calibration module to calibrate the first gas sensor.

Abstract: A portable communication device includes one or more miniature sensors to sense one or more environmental gases. A processor is coupled to the miniature sensors and is configured to enhance location detection by determining a sensor signal transition. The sensor signal transition is caused by subsequent exposures of at least one of the miniature sensors to environmental gases of a first air composition and a second air composition. The first air composition and the second air composition are respectively associated with a first location and a second location.

Abstract: A portable communication device includes a transducer enclosed in an enclosure. An opening allows flow of air between the transducer enclosed in the enclosure and a surrounding environment. The enclosure protects the transducer from misreading due to occlusion of environmental aggressors on the transducer. The enclosure is configured to repel the environmental aggressors away from a surface of the transducer and to keep a portion of the opening unclogged to maintain an air flow to the transducer.

Abstract: A miniature gas sensing device includes a silicon-based substrate embedded with one or more heating elements. One or more electrodes are disposed on the substrate, and a semiconductor gas sensing layer is deposited over the substrate including over the one or more electrodes. The semiconductor gas sensing layer includes sensing grains forming a porous matrix, and a nanometer-scale barrier oxide layer deposited over the sensing grains. The barrier layer separates gas adsorption from surfaces of the sensing grains, and enables electron tunneling based charge transfer process from the sensing grains to the barrier oxide layer. The barrier oxide layer enhances the sensor stability and promotes signal selectivity by favoring detection of strongly oxidizing and/or reducing gas species over less reactive gas species.

Abstract: A miniature gas sensing device includes a silicon-based substrate embedded with multiple first heating elements. A number of electrodes are disposed on the silicon-based substrate. A gas-sensing layer covers the electrodes. A porous or mesoporous adsorbent layer selectively filters components of a gas mixture other than a target gas and allows the target gas to reach the gas-sensing layer. The first heating elements are operable to periodically regenerate sensing capabilities of at least the gas-sensing layer.