Omnidirectional microscopy by ultrasonic sample control
P. Helander, Tuomas Puranen, Antti Meriläinen, Göran Maconi, Antti Penttilä, Maria Gritsevich, I. Kassamakov, Ari Salmi, K. Muinonen, E. Hæggström
Abstract
Omnidirectional microscopy (OM) is an emerging technology capable of enhancing the three-dimensional (3D) microscopy widely applied in life sciences. In OM, the precise position and orientation control of the sample are required. However, current OM technology relies on destructive mechanical methods to hold the samples, such as embedding samples in gel or attaching them to a needle to permit orientation control. A non-contacting alternative is to levitate the sample. Until now, levitation methods have lacked orientation control. We enable omnidirectional access to the sample by introducing a method to control acoustic levitation that provides precise orientation control. Such control around three axes of rotation permits rapid imaging of the sample from any direction using a fixed camera and subsequent 3D shape reconstruction. The control of non-spherical particles is achieved using an asymmetric acoustic field created with a phase-controlled transducer array. Our technology allows robust 3D imaging of delicate samples and their study in a time-lapse manner. We foresee that the described method is not limited to microscopy and optical imaging, but is also compatible with automated sample handling, light-sheet microscopy, wall-less chemistry, and non-contacting tomography.