[1] [1] J. G. Llaurado, "Insulin delivery control systems for diabetics," Int. J. Biomed. Comput. 14, 1–3 (1983).

[2] [2] Y. Y. Luo, X. Y. Xiong, Y. Tian, Z. L. Li, Y. C. Gong, Y. P. Li, "A review of biodegradable polymeric systems for oral insulin delivery," Drug Deliv. 23, 1–10 (2015).

[3] [3] N. Jeandidier, S. Boivin, "Current status and future prospects of parenteral insulin regimens, strategies and delivery systems for diabetes treatment," Adv. Drug Deliv. Rev. 35, 179–198 (1999).

[4] [4] V. I. Sevast'Yanov, L. A. Salomatina, E. G. Kuznetsova, N. V. Yakovleva, V. I. Shumakov, "Transdermal insulin delivery systems," Biomed. Eng. 37, 90–94 (2003).

[5] [5] M. R. Prausnitz, S. Mitragotri, R. Langer, "Current status and future potential of transdermal drug delivery," Nat. Rev. Drug Discov. 3, 115–124 (2004).

[6] [6] J. D. Bos, M. M. Meinardi, "The 500 Dalton rule for the skin penetration of chemical compounds and drugs," Exp. Dermatol. 9, 165–169 (2000).

[7] [7] W. Martanto, S. P. Davis, N. J. Holiday, J. Wang, H. S. Gill, M. R. Prausnitz, "Transdermal delivery of insulin using microneedles in vivo," Pharm. Res. 21, 947–952 (2004).

[8] [8] J. A. Mikszta, J. B. Alarcon, J. M. Brittingham, D. E. Sutter, R. J. Pettis, N. G. Harvey, "Improved genetic immunization via micromechanical disruption of skin-barrier function and targeted epidermal delivery," Nat. Med. 8, 415–419 (2002).

[9] [9] D. G. Koutsonanos, M. D. P. Martin, V. G. Zarnitsyn, S. P. Sullivan, R. W. Compans, M. R. Prausnitz, I. Skountzou, "Transdermal influenza immunization with vaccine-coated microneedle arrays," PLoS One 4, e4773 (2009).

[10] [10] M. R. Prausnitz, "Microneedles for transdermal drug delivery," Adv. Drug Deliv. Rev. 56, 581–587 (2004).

[11] [11] S. Henry, D. V. Mcallister, M. G. Allen, M. R. Prausnitz, "Microfabricated microneedles: A novel approach to transdermal drug delivery," J. Pharm. Sci. 87, 922–925 (1998).

[12] [12] H. S. Gill, M. R. Prausnitz, "Coated microneedles for transdermal delivery," J. Control. Release. 117, 227–237 (2007).

[13] [13] M. Wang, L. Hu, C. Xu, "Recent advances in the design of polymeric microneedles for transdermal drug delivery and biosensing," Lab Chip. 17, 1373–1387 (2017).

[14] [14] J. H. Park, M. G. Allen, M. R. Prausnitz, "Polymer microneedles for controlled-release drug delivery," Pharm. Res. 23, 1008–1019 (2006).

[15] [15] L. Y. Chu, S. O. Choi, M. R. Prausnitz, "Fabrication of dissolving polymer microneedles for controlled drug encapsulation and delivery: Bubble and pedestal microneedle designs," J. Pharm. Sci. 99, 4228–4238 (2010).

[16] [16] I. C. Lee, J. S. He, M. T. Tsai, K. C. Lin, "Fabrication of a novel partially dissolving polymer microneedle patch for transdermal drug delivery," J. Mater. Chem. B 3, 276–285 (2015).

[17] [17] K. Tsioris, W. K. Raja, E. M. Pritchard, B. Panilaitis, D. L. Kaplan, F. G. Omenetto, "Fabrication of silk microneedles for controlled–release drug delivery," Adv. Funct. Mater. 22, 330–335 (2012).

[18] [18] Y. H. Park, K. H. Sang, I. Choi, K. S. Kim, J. Park, N. Choi, B. Kim, J. H. Sung, "Fabrication of degradable carboxymethyl cellulose (CMC) microneedle with laser writing and replica molding process for enhancement of transdermal drug delivery," Biotechnol. Bioproc. E 21, 110–118 (2016).

[19] [19] Y. Ito, T. Nakahigashi, N. Yoshimoto, Y. Ueda, N. Hamasaki, K. Takada, "Transdermal insulin application system with dissolving microneedles," Diabetes. Technol. The. 14, 891–899 (2012).

[20] [20] S. Lau, J. Fei, H. Liu, W. Chen, R. Liu, "Multilayered pyramidal dissolving microneedle patches with flexible pedestals for improving effective drug delivery," J. Control. Release. 265, 113–119 (2017).

[21] [21] D. Liu, B. Yu, G. Jiang, W. Yu, Y. Zhang, B. Xu, "Fabrication of composite microneedles integrated with insulin-loaded CaCO3 microparticles and PVP for transdermal delivery in diabetic rats," Mater. Sci. Eng. C 90, 180–188 (2018).

[22] [22] Y. Zhang, G. Jiang, W. Yu, D. Liu, B. Xu, "Microneedles fabricated from alginate and maltose for transdermal delivery of insulin on diabetic rats," Mater. Sci. Eng. C 85, 18–26 (2018).

[23] [23] D. Liu, Y. Zhang, G. Jiang, W. Yu, B. Xu, J. Zhu, "Fabrication of dissolving microneedles with thermal- responsive coating for NIR-Triggered transdermal delivery of metformin on diabetic rats," ACS Biomater. Sci. Eng. 4, 1687–1695 (2018).

[24] [24] W. Yu, G. Jiang, Y. Zhang, D. Liu, B. Xu, J. Zhou, "Near-infrared light triggered and separable microneedles for transdermal delivery of metformin in diabetic rats," J. Mater. Chem. B 5, 9507–9513 (2017).

[25] [25] T. Rattanapak, J. Birchall, K. Young, M. Ishii, I. Meglinski, T. Rades, S. Hook, "Transcutaneous immunization using microneedles and cubosomes: Mechanistic investigations using optical coherence tomography and two-photon microscopy," J. Control. Release. 172, 894–903 (2013).

[26] [26] K. Yan, H. Todo, K. Sugibayashi, "Transdermal drug delivery by in-skin electroporation using a microneedle array," Int. J. Pharm. 397, 77–83 (2010).

[27] [27] J. Enfield, M. L. O'Connell, K. Lawlor, E. Jonathan, C. O'Mahony, M. Leahy, "In-vivo dynamic characterization of microneedle skin penetration using optical coherence tomography," J. Biomed. Opt. 15, 046001 (2010).

[28] [28] S. A. Coulman, J. C. Birchall, A. Alex, M. Pearton, B. Hofer, C. O'Mahony, W. Drexler, B. Povazay, "In vivo, in situ imaging of microneedle insertion into the skin of human volunteers using optical coherence tomography," Pharm. Res. 28, 66–81 (2011).

[29] [29] R. F. Donnelly, M. J. Garland, D. I. Morrow, K. Migalska, T. R. Singh, R. Majithiya, A. D. Woolfson, "Optical coherence tomography is a valuable tool in the study of the effects of microneedle geometry on skin penetration characteristics and in-skin dissolution," J. Control. Release. 147, 333–341 (2010).

[30] [30] R. Liu, M. Zhang, C. Jin, "In vivo and in situ imaging of controlled-release dissolving silk microneedles into the skin by optical coherence tomography," J. Biophotonics. 10, 870–877 (2017).

[31] [31] M. T. Tsai, I. C. Lee, Z. F. Lee, H. L. Liu, C. C. Wang, Y. C. Choia, H. Y. Chou, J. D. Lee, "In vivo investigation of temporal effects and drug delivery induced by transdermal microneedles with optical coherence tomography," Biomed. Opt. Express 7, 1865–1876 (2016).

[32] [32] D. A. Boas, A. K. Dunn, "Laser speckle contrast imaging in biomedical optics," J. Biomed. Opt. 15, 011109 (2010).

[33] [33] K. R. Forrester, J. Tulip, C. Leonard, C. Stewart, R. C. Bray, "A laser speckle imaging technique for measuring tissue perfusion," IEEE T. Bio-Med. Eng. 51, 2074–2084 (2004).

[34] [34] J. H. Park, M. G. Allen, M. R. Prausnitz, "Biodegradable polymer microneedles: Fabrication, mechanics and transdermal drug delivery," J. Control. Release. 104, 51–66 (2005).

[35] [35] L. Duan, Y. He, R. Zhu, H. Ma, J. Guo, "Development of a spectrum domain 3D optical coherence tomography system," Chin. J. Lasers 36, 2528–2533 (2009).

[36] [36] X. Guo, Z. Guo, H. Wei, H. Yang, Y. He, S. Xie, G. Wu, X. Deng, Q. Zhao, L. Li, "In vivo comparison of the optical clearing efficacy of optical clearing agents in human skin by quantifying permeability using optical coherence tomography," Photochem. Photobiol. 87, 734–740 (2011).

[37] [37] J. Senarathna, A. Rege, N. Li, N. V. Thakor, "Laser speckle contrast imaging: Theory, instrumentation and applications," IEEE Rev. Biomed. Eng. 6, 99– 110 (2013).