By Walt Mills
A new type of imaging that does not require a lens and uses reconfigurable particle-based masks to take multiple shots of an object is being developed by researchers at Penn State. The electric-field directed self-assembling mask technology is expected to have uses in lower-cost and faster disease diagnosis, the enhancement of optical microscopy and may even lead to thinner cell phone technology.
How it works
A mask made of microscopic gold wires is placed near the object that will be imaged. The mask scatters the light reflected off the object and the light is collected by an image sensor. The particles in the mask are then rearranged by an electric current, giving a new mask with every iteration, and the new image is recorded. The scattered light can then be computationally reconstructed into the original object image using the multiple light captures, resulting in highly improved resolution and quality.
“We are not the only group to do lens-free imaging,” explains Jennifer Miller, a doctoral candidate in chemistry and a first author on a paper published online this week in ACS Nano. “What is different about our work is that typically you would need to make multiple masks and physically move them around to get multiple images. This becomes bulky and expensive and negates some of the simplicity that is the advantage of lens-free imaging.”
Adds co-first author Cheng-Yu Wang, doctoral candidate in electrical engineering, “Traditional masks are passive. We can add functionalization to our microwire, like polarization, selectivity and plasmonic effects, that make our imaging system more powerful.”
In typical microscopy, there exists a trade-off between the field of view and the power of the resolution, so a 10x field is wider than a100x field. By using a lens-free imaging technology, it is possible to combine a wide field of view with high magnification for lower-cost images and faster diagnosis of disease. This could be especially useful in developing countries where high-end microscopes are not available.
In the case of cell phones, one major contributor to their bulk is due to the camera lens needing to be a certain distance to the detector. A lens-free camera could help minimize the space requirement. Likewise, a lens-free system added to a cell phone could turn the cell phone into a low-power microscope.
Along with Miller and Yang, senior authors on the ACS Nano paper, titled “Particle-based reconfigurable scattering masks for lensless imaging,” are Christine Keating, Distinguished Professor of Chemistry, and Zhiwen Liu, professor of electrical engineering.
This work was funded by the Penn State MRSEC, Center for Nanoscale Science, and by the National Science Foundation.
Penn State has filed a patent application for this technology.