A medium designed to be applied to a patient's unbroken skin surface (excludes the eye surface) to provide a coupling between an analytical or therapeutic device (e.g., ultrasound transducer, optical glucose monitoring system, transcutaneous electrical stimulator) and the patient, allowing for the emission and reception of energy/signals (e.g., electrical current, light) that pass through the skin during an examination or treatment. It is in the form of a fluid-like gel that may also assist in moving the parent device smoothly over the skin. It may be used by a healthcare professional in a clinical setting and layperson in the home. After application, this device cannot be reused.