A system for measuring the diameter of a human hair (50), the system comprising: a mobile device (20); and a reference card (10) including a hair attachment mechanism (11a, 11b); the mobile device configured to convert an image of a human hair attached to the reference card by the attachment mechanism into a measurement of the diameter of the human hair, using the size of the reference card itself and/or the size of a calibration marker (12) on a surface of the reference card as a size reference.

Examples of systems and methods described herein may estimate the bilirubin level of an adult subject based on image data associated with a portion of the eye of the subject (e.g., a color of the sclera). Accessories are described which may facilitate bilirubin estimation, including sensor shields and calibration frames.

Methods and devices are provided for analyzing acetone in breath. One such method comprises disposing a reactant in a reaction zone within the breath analysis device, wherein the reactant comprises a primary amine disposed on a surface, and wherein the reaction zone has an optical characteristic that is at a reference level. It also comprises pre-storing a liquid nitroprusside solution within the breath analysis device separately from the reactant. The method further comprises using the breath analysis device to cause the breath to contact the reactant in the reaction zone so that the acetone in the breath reacts with the reactant to form a reaction product and, after the reaction product has been formed, using the breath analysis device to cause the nitroprusside solution to contact and react with the reaction product and to facilitate a change in the optical characteristic of the reaction zone relative to the reference level. The method also comprises using the breath analysis device to detect the change in the optical characteristic to sense the acetone in the breath. Apparatuses that use these methods are also described.

Devices and methods are provide for facilitating registration and calibration of surface imaging systems. Tracking marker support structures are described that include one or more fiducial reference markers, where the tracking marker support structures are configured to be removably and securely attached to a skeletal region of a patient. Methods are provided in which a tracking marker support structure is attached to a skeletal region in a pre-selected orientation, thereby establishing an intraoperative reference direction associated with the intraoperative position of the patient, which is employed for guiding the initial registration between intraoperatively acquired surface data and volumetric image data. In other example embodiments, the tracking marker support structure may be employed for assessing the validity of a calibration transformation between a tracking system and a surface imaging system. Example methods are also provided to detect whether or not a tracking marker support structure has moved from its initial position during a procedure.

A method for testing an optical investigation system, with an imaging device, a video camera and a light source for optical investigation of an object including a reference surface with predetermined optical properties being illuminated with illuminating light from a light source. An image of the reference surface is recorded by the imaging device and the video camera. An operating condition of the video camera that prevails during the recording of the image is recorded. The functionality or another property of the investigation system is determined on the basis of the recorded operating condition.

A process for calibrating a glucose sensor under sterile conditions includes providing separate, sterile, glucose-containing calibration fluids, each having a different glucose concentration, and in turn providing these fluids to a sensing zone containing a sensing probe of a glucose sensor. Each solution is typically, in turn, propelled into the sensing zone, thus flushing out used fluid already present in the sensing zone. The process provides rapid calibration of a glucose sensor in a sterile fashion and is therefore appropriate for point-of-use calibration.

A system and method, for measuring phase delay and amplitude of a near infrared signal emanating from tissue of an animal subject in response a near infrared signal input to such tissue, operate by processing a signal from an optical detector and a corresponding signal from an optical detector emulation circuit. In some aspects, the processed signals are fed into a phase delay detection system that provides an output thereof a digital measure of the phase delay of the received optical signal.

A digital image is captured. The captured digital image includes a calibration pattern. The calibration pattern includes displayed information about the calibration pattern. The displayed information is read to obtain calibration information about the captured digital image.

A 3D calibration body for spatial calibration of an optical imaging system includes a transparent body and calibration marks embedded in a volume of the transparent body. At least some of the calibration marks are selectively activatable and deactivatable, wherein an activated calibration mark is visible in the visible spectral range and a deactivated calibration mark is not visible in the visible spectral range.

An oxygen saturation measuring apparatus capable of measuring arterial blood oxidation saturation (SpO2), and tissue oxygen saturation (rSO2), safely, easily and economically at a desired position of a biological body for a long time continuously. A ROM stores the distance information between a light emitting unit and a light receiving unit situated corresponding to the depth of a target intended to be measured for tissue oxygen saturation, a light emission driving unit makes the light emitting unit emit light in an amount of light corresponding to the distance information, MPU makes the light emitting unit emit a pulses capable of measuring the tissue oxygen saturation, MPU applies pulse capable of measuring the tissue oxygen saturation from the light emission driving unit to the light emitting unit, and the pulse increasing unit increases the amount of pulses from MPU for a predetermined time to pulses capable of measuring the arterial blood oxygen saturation.