A sensor includes a sensor pad configured to be disposed on a portion of a patient's body. A light sheet is disposed on the sensor pad and has a first substrate and a second substrate spaced from one another. The light sheet further includes a light source configured to emit near-infrared light and a light detector configured to detect near-infrared light. The light source and the light detector are disposed between the substrates. The sensor pad is configured to allow light generated by the light source to travel through the portion of the patient's body to the light detector. The light received by the light detector is indicative of oxygen saturation of the portion of the patient's body through which the light travelled.