SPIM setup consisted of an Olympus N4X-PF low magnification air objective for detection
and two cylindrical lenses aligned orthogonal to the detection for double sided
light-sheet illumination. The sample was illuminated alternately from two
sides. The alternating illumination was controlled via a flipper mirror (8892-K-M, New Focus, USA). The
sample chamber was 3d printed and had two windows for illumination and one
window for detection of the sample. The electromagnets were hold by the sample
chamber and assembled in a tetrahedral geometry to enable three-dimensional
control of sample’s orientation. The applied current was remotely controlled
via a programmable power supply (QL355P, Aim-TTi, United
Kingdom) and a manual
switch. The focus of the four electromagnet-tips coincided with the sample. The
sample was inserted from the top within a FEP tube orthogonal to the
detection objective and to the illumination objective. To scan the sample the
sample chamber was positioned on a motorized linear stage (M111.1DG, Physik
Instrumente, Germany) and moved relative to the detection objective. To correct
for the different path length in water and air the detection objective was also
placed on a linear stage (M111.1DG, Physik Instrumente, Germany) and moved
accordingly. For wide-field illumination a LED is placed behind the sample. For
light-sheet illumination a single color (488nm) Coherent Sapphire laser (488-30
CDRH) was used. The wide-field and fluorescence signals were detected with a sCMOS
camera (Zyla 5.5, Andor, United Kingdom).
Electromagnets
The electromagnets were custom-built and
consisted of a magnetic core made from HyMu 80 alloy (National Electronic
Alloys, USA) and a solenoid. The bobbin was made from Teflon and a high
resistance wire was wind up hundreds of times to create a high magnetic field.
The magnetic core had a diameter of 6mm and was tapered to create a strong
magnetic field gradient. The inner diameter of the bobbin was 6mm that the
magnetic core could be inserted.