title: Optical lens-microneedle array for percutaneous light delivery.
abstract: The limited penetration depth of light in skin tissues is a practical bottleneck in dermatologic applications of light-induced therapies, including anti-microbial blue light therapy and photodynamic skin cancer therapy. Here, we demonstrate a novel device, termed optical microneedle array (OMNA), for percutaneous light delivery. A prototype device with a 11 by 11 array of needles at a spacing of 1 mm and a length of 1.6 mm was fabricated by press-molding poly-(lactic acid) (PLA) polymers. The device also incorporates a matched microlens array that focuses the light through the needle tips at specific points to achieve an optimal intensity profile in the tissue. In experiments done with bovine tissues, the OMNA enabled us to deliver a total of 7.5% of the input photons at a wavelength of 491 nm, compared to only 0.85% without the device. This 9-fold enhancement of light delivery was close to the prediction of 10.8 dB by ray-tracing simulation and is expected to increase the effective treatment depth of anti-microbial blue light therapy significantly from 1.3 to 2.5 mm in human skin.
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; Department of Physics, Korea University, Seoul 136-701, South Korea; These authors contributed equally.
authors.forename: Moonseok
authors.initials: M
authors.lastname: Kim
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; These authors contributed equally.
authors.forename: Jeesoo
authors.initials: J
authors.lastname: An
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; These authors contributed equally.
authors.forename: Ki Su
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; Department of Biomedical Engineering, Sungkyunkwan University; Center for Neuroscience and Imaging Research, Institute for Basic Science, Suwon, South Korea.
authors.forename: Myunghwan
authors.initials: M
authors.lastname: Choi
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; Condensed Matter Department, J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000, Ljubljana, Slovenia.
authors.forename: Matjaž
authors.initials: M
authors.lastname: Humar
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; Harvard-MIT Health Sciences and Technology, Cambridge, MA 02139, USA.
authors.forename: Sheldon J J
authors.initials: SJ
authors.lastname: Kwok
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA.
authors.forename: Tianhong
authors.initials: T
authors.lastname: Dai
authors.affiliation: Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, MA 02139, USA; Harvard-MIT Health Sciences and Technology, Cambridge, MA 02139, USA.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Yun
keywords: (160.1435) Biomaterials; (170.0170) Medical optics and biotechnology; (170.3660) Light propagation in tissues; (170.5180) Photodynamic therapy; (230.0230) Optical devices