Chemical and Biological Diagnostics Using Fully Insulated Ultracompliant Thermal Probes

This paper reports on the detection of nano-scale chemical variations in photosensitive polymers and biological variations in ovarian cancerous tumor cells that have been accomplished for the first time using scanning thermal probes that we have developed. A probe of 250 μm length, 50 μm width, and 3 μm thickness has a measured spring constant of 0.082 N/m. Lateral spatial resolution of <50 nm, topographic resolution of <1 nm and thermal resolution of <1.2 mK are demonstrated. Wet scanning capability, which widens the possibility of biochemical applications, is also demonstrated for the first time. The structure, fabrication, and assembly of the probe and the interface circuit used for these experiments are described.