Disposable Heater Arrays Using Printed Silver Patterns on Polyethylene Terephthalate for Multipurpose Applications

Flexible, semitransparent and robust heating arrays have been designed by grayscale printing as ready-to-use devices for point-of-care application. A perforated Ag mesh is first fabricated with tunable features by controllably varying the toner grayscale value during laser printer on PET. The resistance could be varied between 1 to 2 by tuning the Ag fill factor from 50 to 70%. The Ag/PET heater based on joule heating is able to attain highly stable temperatures upto approximate to 135 degrees C maintained over long hours. Since temperature is directly related to resistance, this provides a fine temperature knob without any cumbersome processing steps. The merit of design allows individual heating elements to attain stable temperatures at low voltages (approximate to 1.5V) without any interference from neighboring heaters of the array, thus resulting in a thermal library. A laptop USB with 5.1V output is able to power the thermal library for temperatures in the range of 30-60 degrees C, useful in many practical applications. It is a multipurpose disposable chip for in-situ transmission microscopy that can be utilized for bioassay and point-of-care diagnostics, as demonstrated in the study.