Transducer transfer stack

A method of forming a transfer stack for transferring a portion of a foil within a perimeter that includes a transducer to an article such as a medical device or a medical needle;

• the method comprising the steps of:
• providing a carrier substrate;
• providing a foil comprising a transducer that is laterally surrounded by a perimeter, the perimeter being within the lateral extent of the foil;
• and
• providing an adhesive layer;
• attaching a first surface of the foil to the carrier substrate;
• attaching the adhesive layer to the second surface of the foil;
• wherein the first surface of the foil is separable from the carrier substrate by applying in a direction normal to the carrier substrate and at an edge of the foil a peeling force that overcomes a first peel retaining force;
• and
• wherein the adhesive layer is configured to provide adhesion between the foil and an article such that when the article is attached to the foil via the adhesive layer the second surface of the foil is separable from the surface of the article by in a direction normal to the surface of the article and at the edge of the foil a peeling force that overcomes a second peel retaining force;
• and
• wherein the second peel retaining force is greater than the first peel retaining force;
• and
• cutting the foil along at least a portion of the perimeter that includes the transducer, such that when the article is attached to the foil via the adhesive layer and subsequently peeled in a direction normal to the carrier substrate the portion of the foil within the perimeter becomes separated from the carrier substrate at the perimeter by overcoming the first peel retaining force and the portion of the foil within the perimeter remains attached to the article.