Abstract: A method of monitoring at least one fluid compartment of a body comprising: illuminating the skin with light that stimulates photoacoustic waves in the skin; and using the photoacoustic waves to measure change in the volume of the fluid compartment.

Abstract: A sticker for attaching a photoacoustic sensor or portion thereof to the skin of a patient comprising: a substrate; an adhesive layer on the substrate suitable for adhering the sticker to the skin; apparatus for attaching the sticker to the photoacoustic sensor; and at least one device for presenting an identifying ID code.

Abstract: Apparatus for assaying an analyte in a patient's body comprising: at least one sensor unit mountable to a region of the patient's skin comprising at least one light source that illuminates a tissue region below the skin with light that generates photoacoustic waves therein and at least one acoustic transducer that generates signals responsive to the photoacoustic waves; and a control unit configured to be mounted to a different part of the body and comprising a controller for controlling the at least one light source and at least one acoustic transducer and receiving the signals generated by the at least one acoustic transducer.

Abstract: A method for determining temperature of a material (32) comprising: measuring at least one of the real and imaginary part of the permittivity of the material (32) at each of at least one frequency (36) for which substantially only a single component of the material contributes to the dielectric permittivity of the material (32), for which known component the permittivity as a function of temperature is known; and using at least one of the determined real and imaginary part of the permittivity at each of the at least one frequency and the dependence of the permittivity of the known component on temperature to determine temperature of the known component and thereby of the material (32).

Abstract: Determining the temperature of the water by measuring the absorption coefficient of water (32). The method for determining temperature of a first substance comprising acquiring a measurement of the absorption coefficient of the first substance at least one wavelength (30); and determining the temperature using the measurement of the absorption coefficient and known values of the absorption coefficient as a function of temperature at the at least one wavelength.

Abstract: A method for assaying a component of a localized region of interest in a body comprising: illuminating the region with at least one pulse of radiation having a wavelength at which the radiation is absorbed by the component to generate a change in an acoustic property of the region; transmitting ultrasound so that it is incident on the region; measuring at least one effect of the change on the incident ultrasound; using the measured at least one effect to determine an absorption coefficient for the radiation in the region; and using the determined absorption coefficient to determine concentration of the component in the region.