https://doi.org/10.5061/dryad.9w0vt4bn7

The dataset contains microscopy videos of migrating microrobots recorded with an Olympus IX71 microscope. The microscopy videos were recorded at different electric field strengths and frequencies, and at varying buffer concentrations. These videos form the basis for Figures 5 and 6 in the associated publication. Additionally, the dataset contains ImageJ macros for manual measurement of dimer migration speeds, as well as a .csv files containing the measurements generated with these macros.

Description of the data and file structure

There are two datasets. The first is provided in the folders "MgCl_and_NaCl.zip" and "NaOH_and_trisHCl.zip," each containing two folders for a different electrolyte type.

The second is "voltage_and_freq.zip", which contains three folders, each for a different microrobot, tested at various frequencies and voltages.
Inside the folders, there are microscopy videos from which we extracted the microrobot velocities for both the voltage-frequency plot and the analysis of velocities at varying salt concentrations.

The filenames of the videos specify the experimental conditions under which we conducted the experiments.

For instance, vpp11_250hz_0uMMgCl_50uMnaoh_2 denotes an experiment carried out at an amplifier voltage of 11 Vpp, a frequency of 250 Hz, a MgCl concentration of 0 µM, and an NaOH concentration of 50 µM. The final digit, 2, indicates that this is the second video recorded under these conditions.
Adjacent to the TIFF files in the directory, we provide metadata files that include timestamps for each recorded frame, measured in milliseconds.
Note that the resolution information in the TIFF files is incorrect due to the manual insertion of the objectives. Although we utilized a 20x objective, the scale is saved for a 4x objective. The correct scale may be calculated using the corresponding fraction. The actual concentration of Tris is twice the value stated in the filename. This discrepancy arose because we recorded ionic strength rather than concentration. Tris was titrated to a pH of 8.4, corresponding to its pKs, where half of the Tris exists in its ionic form.

Code/Software

Within the subfolders designated for frequency and voltage plots, we have included two ImageJ macros.
Each subfolder contains a distinct macro that must be installed via Plugins -> Macros -> Install in ImageJ to become usable.
We employed these macros for manual measurement of the microswimmer velocities.

For frequency and voltage measurements:

• Upon installing the macro, the user should first select the multipoint tool.
• In the video, the user marks both the starting and ending positions of a particle within the relevant frames.
• Pressing 's' or 'r' will automatically save these positions; 's' is used for a swimmer measurement, while 'r' designates a reference particle measurement.

For salt measurements:

• The macro offers three optional buttons—'u,' 'd,' and 'r.'
• The 'u' button is for a swimmer pointing upwards with the larger particle, 'd' for downwards, and 'r' for reference particles.

Measurements

We include the measurements we made with the macros in the corresponding folders where the raw data are stored as CSV files, named "Results_*.csv."
For buffer measurements, the file is named "Results_ud.csv."

Each measurement is represented by two successive lines in the file.

• The first line indicates the start position of a microswimmer.
• The second line represents the end position.

The column headers are "X, Y, Slice, direction, type, title, dir"

• The first column is simply an increasing number with no specific meaning.
• X and Y represent the coordinates in pixels.
• Slice refers to the frame number where the measurement was made.
• Direction indicates whether the microswimmer points with the larger particle upwards or downwards.
• Title is the name of the microscopy video where the measurement was made.
• Dir specifies the directory where the video was located when the measurement was conducted.

For frequency and voltage measurements, the file structure is similar, but the direction column is omitted, as all dimers move with the larger particle in front.