FIG 1.

The temperature gradient-forming device, including the control unit. This low-budget custom-made device consists of a stainless steel plate (A) located on a circuit board (B). Two independently working heating elements (C) located at the left and right ends of the steel plate allow heating up to 110°C. A rectangular glass capillary containing the cells to be analyzed is placed into the rectangular groove milled into the steel plate; the five small holes (the middle one is indicated by the arrow) for observation of cells are 5 mm apart each. On the back side of the circuit board, five temperature sensors are located close to the observation holes. The control unit (D) shows the actual temperatures at the left- and rightmost observation holes (here 74 and 110°C). The temperatures of the three middle observation holes (here 88°C for the middle hole indicated by the arrow) can be accessed using the black switch (E). The placement of the circuit board onto the xy-stage of any conventional upright light microscope converts it into a thermomicroscope.