Abstract: A measurement device for measuring a concentration of a component of a gas mixture includes a chamber that contains the gas mixture, a light source that emits light into the chamber, the emitted light having a wavelength between 230 nm and 320 nm, and a light sensor that detects a portion of the light from the light source that has propagated through the gas mixture. A processor is configured to determine the concentration of the component of the gas mixture based on the portion of the light emitted from the light source that is detected by the light sensor. The light source may include one or more LEDs, each having a central wavelength of light emission between 270 nm and 320 nm and a linewidth of less than 50 nm. The device may be employed to determine acetone concentration in exhaled breath, which may be indicative of diabetes or other health conditions.

Abstract: A measurement device for measuring a concentration of a component of a gas mixture includes a chamber that contains the gas mixture, a light source that emits light into the chamber, the emitted light having a wavelength between 230 nm and 320 nm, and a light sensor that detects a portion of the light from the light source that has propagated through the gas mixture. A processor is configured to determine the concentration of the component of the gas mixture based on the portion of the light emitted from the light source that is detected by the light sensor. The light source may include one or more LEDs, each having a central wavelength of light emission between 270 nm and 320 nm and a linewidth of less than 50 nm. The device may be employed to determine acetone concentration in exhaled breath, which may be indicative of diabetes or other health conditions.

Abstract: A measurement device for measuring a concentration of a component of a gas mixture includes a chamber that contains the gas mixture, a light source that emits light into the chamber, the emitted light having a wavelength between 230 nm and 320 nm, and a light sensor that detects a portion of the light from the light source that has propagated through the gas mixture. A processor is configured to determine the concentration of the component of the gas mixture based on the portion of the light emitted from the light source that is detected by the light sensor. The light source may include one or more LEDs, each having a central wavelength of light emission between 270 nm and 320 nm and a linewidth of less than 50 nm. The device may be employed to determine acetone concentration in exhaled breath, which may be indicative of diabetes or other health conditions.

Abstract: An semiconductor structure comprises a first quantum well having a first state (E3) with an energy that is greater than an energy of a lower state (E1) by a first energy difference, a quantum well structure (100) adjacent to the first quantum well and having at least a second state (E4) having an energy level which is resonant with the first state (E3) of the first quantum well, a second quantum well having at least a third state (E2) to collect electrons from the second state (E4) of the quantum well structure through a non-radiative mechanism and a fourth state (E5). An energy of the fourth state of the second quantum well is greater than an energy of the third state (E2) by a second energy difference. The structure can absorb two photons, one in the first quantum well by excitation of a carrier from the lower energy state (E1) to the first state (E3) and another in the second quantum well by excitation of a carrier from the third state (E2) to the fourth state (E5).

Abstract: A measurement device for measuring a concentration of a component of a gas mixture includes a chamber that contains the gas mixture, a light source that emits light into the chamber, the emitted light having a wavelength between 230 nm and 320 nm, and a light sensor that detects a portion of the light from the light source that has propagated through the gas mixture. A processor is configured to determine the concentration of the component of the gas mixture based on the portion of the light emitted from the light source that is detected by the light sensor. The light source may include one or more LEDs, each having a central wavelength of light emission between 270 nm and 320 nm and a linewidth of less than 50 nm. The device may be employed to determine acetone concentration in exhaled breath, which may be indicative of diabetes or other health conditions.

Abstract: A photovoltaic energy harvesting (PVEH) device comprises a single-junction photovoltaic cell. The photovoltaic cell includes a light converting element made of a wide band-gap III-V active material spectrally matched to an ambient light source, a light receiving side that is free from front metal contact gridlines, and at least one discrete metal contact element placed on the light receiving side that realizes power extraction. The active material of the light converting element may be made of (Al)GaInP compounds. The active material of the light converting element may be spectrally matched to ambient light in the form of at least one of an artificial light source and natural sunlight, and combinations thereof. The PVEH device may have a plurality of photovoltaic cells inter-connected in series to achieve a higher open-circuit voltage. A total fractional power loss due to series resistance, shunt resistance and contact shading is less than 20%.

Abstract: An semiconductor structure comprises a first quantum well having a first state (E3) with an energy that is greater than an energy of a lower state (E1) by a first energy difference, a quantum well structure (100) adjacent to the first quantum well and having at least a second state (E4) having an energy level which is resonant with the first state (E3) of the first quantum well, a second quantum well having at least a third state (E2) to collect electrons from the second state (E4) of the quantum well structure through a non-radiative mechanism and a fourth state (E5). An energy of the fourth state of the second quantum well is greater than an energy of the third state (E2) by a second energy difference. The structure can absorb two photons, one in the first quantum well by excitation of a carrier from the lower energy state (E1) to the first state (E3) and another in the second quantum well by excitation of a carrier from the third state (E2) to the fourth state (E5).

Abstract: A lighting device includes a transparent optical cavity having an exit surface including a specularly reflective material arranged to reflect light into the cavity, the exit surface having a plurality of apertures formed therein, a base surface including a specularly reflective material arranged to reflect light into the cavity, and at least one light receiving surface arranged relative to the base surface and configured to receive light from a light source. The plurality of apertures are arranged to maximize at least one of uniformity, angular distribution, efficiency or luminous intensity of light exiting the exit surface, and a distribution of light received at the light receiving surface is altered by at least one of a combination of the exit surface and the base surface, or the light receiving surface.