title: A high-precision micropipette sensor for cellular-level real-time thermal characterization.
abstract: We report herein development of a novel glass micropipette thermal sensor fabricated in a cost-effective manner, which is capable of measuring steady thermal fluctuation at spatial resolution of ∼2 μm with an accuracy of ±0.01 °C. We produced and tested various micrometer-sized sensors, ranging from 2 μm to 30 μm. The sensor comprises unleaded low-melting-point solder alloy (Sn-based) as a core metal inside a pulled borosilicate glass pipette and a thin film of nickel coating outside, creating a thermocouple junction at the tip. The sensor was calibrated using a thermally insulated calibration chamber, the temperature of which can be controlled with an accuracy of ±0.01 °C, and the thermoelectric power (Seebeck coefficient) of the sensor was recorded from 8.46 to 8.86 μV/°C. We have demonstrated the capability of measuring temperatures at a cellular level by inserting our temperature sensor into the membrane of a live retinal pigment epithelium cell subjected to a laser beam with a focal spot of 6 μm. We measured transient temperature profiles and the maximum temperatures were in the range of 38-55 ± 0.5 °C.
authors.affiliation: Department of Mechanical and Energy Engineering, University of North Texas, 3940 N. Elm St, Denton, TX 76207, USA. rameshstha@yahoo.com
authors.forename: Ramesh
authors.initials: R
authors.lastname: Shrestha
authors.forename: Tae-Youl
authors.initials: TY
authors.lastname: Choi
authors.forename: Wonseok
authors.initials: W
authors.lastname: Chang
authors.forename: Donsik
authors.initials: D
authors.lastname: Kim
mesh_terms: D002138:Calibration; D003362:Cost-Benefit Analysis; D006801:Humans; D015203:Reproducibility of Results; D055213:Retinal Pigment Epithelium / Q000166:cytology*