In many medical applications it is desirable to hold one or more sensors in contact with a patient's tissue such that various non-invasive measurements of physiological events may be made. For example, pulse oximeter sensors may be held in contact with a patient's tissue to non-invasively determine pulse rate and/or blood oxygenation levels. When using a pulse oximetry sensor, it is important to properly position the sensor relative to the patient's tissue to ensure its proper operation. If the sensor is held too loosely relative to the tissue, it may not function; in contrast, if the sensor is pressed into the tissue, it may interfere with the physiological properties it is supposed to monitor.
Pulse oximeter sensors generally comprise a detector and at least one light source, which may be focused on or through a patient's tissue. Reflective type pulse oximeter sensors generally focus the light source(s) on the patient's tissue and the detector ‘receives’ light reflected back. Accordingly, reflective type sensors' light source(s) and detector(s) may be contained in a single discrete unit and be held in contact with the same surface on a patient's tissue. Transmittance type pulse oximeter sensors, which transmit light through tissue a patient's tissue, require that the light source(s) and detector(s) be held to a patient's tissue such that an optical path through the tissue exists between the light source(s) and the detector(s) (e.g., through a finger, ear lobe, hand, foot etc.). Therefore, transmittance type sensors generally have light source(s) and detector(s) that are somewhat separated. Irrespective of the type of pulse oximetry sensor utilized, it is important that a holder provide flexibility in positioning the sensor in order to provide good conformance between the light source(s), detector(s), and the patient's tissue.
There are a number of additional considerations for sensor holders. First, the sensors used with such holders should have the ability to achieve a reliable interface between the sensor and the patient's tissue. Inherent in this first design consideration is the need to securely hold a sensor in place relative to the patient's tissue so the holder and sensor are resistant to unintended removal and/or slippage relative to the tissue. This is especially important for patients that are unable to control their movements or are likely to interfere with the sensor, such as infants. Second, the holder and sensor should be adapted for ready application and removal from the patient with minimal patient discomfort and ease of use for the applicator. Finally, the holder and sensor should provide a gentle interface with the patient's skin.