"Blood vessel networks can be several centimeters in length, but walls of the smallest branches (capillaries) are only a few micrometers thick. The same applies with any tissue. Many tissues may be large, but they all have important features on the microscale," says team member Shaun Gittard of the LZH. The team notes that using conventional 2PP to manufacture the tissue scaffolds for such structures could be prohibitively slow. They address the problem by using a computer-controlled hologram to split the 2PP laser into multiple beams, creating up to 16 different focus points that can work simultaneously.
"As an example, take the time for fabricating a single layered, 1-millimeter square with 100 nanometer resolution," the authors write. "With conventional single-focus 2PP at one millimeter per second, the fabrication time would be 2 hours and 47 minutes. In contrast, with 16 foci this same area could be scanned in merely 10 minutes." Or, in other words, many foci make light work.
The team first tested their multiple foci system by creating 16 miniature Venus statues, each so small as to be invisible to the human eye (see figure 1). "The Venus is kind of a logo of our research group," says Gittard. "We have used it as a familiar demonstration structure for various fabrication techniques."
In addition to replicas of classic Greek artwork, the team also used the new technique to manufacture cylindrical tissue scaffolds (see figures 2) and an array of microneedles. Less than a half millimeter wide, rocket-shaped microneedles can be used to provide painless injections or take blood samples, notes Gittard (see figure 3). "One of the biggest promises in the future is real-time, pain-free glucose sensing and insulin delive
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Optical Society of America