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Design of the LEGO microscope. (a, b) A photograph and a schematic representation of the microscope, (c) the LED that illuminates the sample from below, (d) the threaded system that adjusts the focus of the microscope by moving the objective, (e) 2 objectives containing a replacement smartphone lens with a 3.85-mm focal distance (left) and a glass lens with a 26.5-mm focal distance (right), (f) the second lens consisting of 2 acrylic lenses in its holder just below the eyepiece, (g) a smartphone used as a camera by adapting the eyepiece.
Fraction of correctly answered questions on subjects of natural sciences and microscopy, before and after using the LEGO microscope. The bars show the average results of 5 questions on either of the subjects, filled in by 8 students in the age range between 9 and 13 y. The black dots correspond to the results of individual students. There was no significant (ns) change in the results of the general science questions: from 78 ± 21% to 83 ± 21% correctly answered questions, but a statistically significant improvement (***, P < 0.001) was observed for the questions on microscopy, from 50 ± 17% to 83 ± 12% correct answers.
Examples of experiments conducted with the LEGO microscope. (a) Image of a sodium chloride crystal. (b) Time lapse of an osmotic shock in red onion cells. After approximately 30 s, a 1 M NaCl solution is flowed in. Subsequently, water leaves the cells, causing the cell membranes to detach from the cell walls. After approximately 5 min, distilled water is flowed in, washing away the 1 M NaCl solution, and the cells return to their original volume. (c) Time lapse of the movement of an Artemia shrimp in water. (d) Time lapse of the movement of 2 water fleas in water. The scale bars in panels a, b, and d are 100 μm.
Experimentally determining the magnification of the microscope. (Top) Imaging of squared paper without lenses in place. The width of each square is 5 mm. (Bottom) Imaging of the USAF Resolution target with the high-magnification objective and an f = 53 mm lens near the eyepiece. The length of the bar next to the number 4 is 27.6 μm. Note that for a correct determination of the magnification, the (digital) zoom of the camera has to be the same for both images.
Schematic overview of the light path in the microscope. The object (here depicted as an arrow) forms an inverted intermediate image in the focus of the second lens. The second lens then sends collimated light to the observer.
Quantifying the resolution of the microscope with a high-magnification and a low-magnification objective. (a, b) Using the known width of the lines in the USAF Resolution Test Target, the conversion factor from pixels to micrometers can be calculated. In these panels, the width of bars crossed by the red lines are 2.76 and 11.05 μm, respectively, and the corresponding intensity profiles along the lines are shown directly below. (c, d) Intensity profiles along the red lines using the pixel-to-micrometer conversion factor obtained from the calibration slide, (e, f) intensity profile along a single bar (black) that has been fitted (red) with a cumulative distribution function of a normal distribution.