Stacked adhesive optical sensor

A sensor comprising:

• a base having an opening therein;
• a lid sized to be disposed in the opening in the base, wherein one end of the lid is connected to the base by a pivotal connection;
• a clasp connected with another end of the lid, the clasp configured to engage the base;
• an emitter coupled to the lid;
• and
• a detector coupled to the lid.

A sensor comprising:

• a flexible base having an opening therein;
• a flexible lid sized to be disposed in the opening in the base, wherein one end of the lid is connected to the base by a pivotal connection;
• a clasp connected with another end of the clasp configured to engage the base;
• an emitter coupled to the lid;
• and
• a detector coupled to the lid.

A sensor comprising:

• a base having an opening therein;
• a lid sized to be disposed in the opening i the base, wherein one end of the lid is connected to the base by a pivotal conection;
• a clasp connected with another end of the lid, the clasp configured to engage the base;
• an emitter coupled to the lid;
• a first lens coupled to the emitter;
• a detector coupled to the lid;
• and
• a second lens coupled to the detector, wherein the first lens and the second lens protrude beyond a patient contact side of the base when the lid is disposed in the opening in the base.