E.S. Polsen, M. Bedewy, A.J. Hart. Decoupled control of carbon nanotube forest diameter and density by continuous-feed convective assembly of catalyst particles. Small, 9: 2564–2575. [http://dx.doi.org/10.1002/smll.201202878] The widespread potential application of vertically aligned carbon nanotube (CNT) forests have stimulated recent work on large-area chemical vapor deposition growth methods, but improved control of the catalyst particles is needed to overcome limitations…

M.J. Roberts, N. Bhatt, C.M. Voge, E.R. Meshot, J.P. Stegemann, A.J. Hart. Self-assembly of suspended collagen films and their viability as cell culture substrates.  Journal of Materials Chemistry B, 2013, 1 (37), 4711 – 4718. [http://dx.doi.org/10.1039/C3TB20800A] We present the fabrication and mechanical properties of thin collagen networks self-assembled in a suspended configuration over micropost arrays. These…

F.A. Hill, T.F. Havel, A.J. Hart, C. Livermore. Enhancing the tensile properties of continuous millimeter-scale carbon nanotube fibers by densification. ACS Applied Materials and Interfaces, 2013, 5 (15), pp 7198–7207. [http://pubs.acs.org/doi/abs/10.1021/am401524q] This work presents a study of the tensile mechanical properties of millimeter-long fibers comprising carbon nanotubes (CNTs). These CNT fibers are made of aligned, loosely packed parallel networks of CNTs…

E.S. Polsen, A.G. Stevens, A.J. Hart. Laser printing of nanoparticle toner enables digital control of micropatterned carbon nanotube growth. ACS Applied Materials and Interfaces 5(9):3656–3662, 2013. [http://dx.doi.org/10.1021/am400148t] Commercialization of materials utilizing patterned carbon nanotube (CNT) forests, such as hierarchical composite structures, dry adhesives, and contact probe arrays, will require catalyst patterning techniques that do not…

C.R. Oliver, E.S. Polsen, E.R. Meshot, S. Tawfick, S.J. Park, M. Bedewy, A.J. Hart. A statistical analysis of variation in laboratory growth of carbon nanotube forests and recommendations for improvement of process consistency. ACS Nano 7(4):3565–3580, 2013. [http://dx.doi.org/10.1021/nn400507y] While many promising applications have been demonstrated for vertically aligned carbon nanotube (CNT) forests, lack of consistency…

S.J. Park, A.J. Schmidt, M. Bedewy, A.J. Hart. Measurement of carbon nanotube microstructure density by optical attenuation and observation of size-dependent density variations. Physical Chemistry Chemical Physics 15:11511-11519, 2013. [http://dx.doi.org/10.1039/C3CP51415C] Engineering the packing density of CNT forest microstructures is vital to applications such as electrical interconnects, micro-contact probes, and thermal interface materials. For CNT forests on centimeter-scale substrates, weight…

A. Ya’akobovitz, D. Copic, J. Beroz, A.J. Hart. Nanoscale displacement measurement of microdevices via interpolation-based edge tracking of optical images. Journal of Micromechanics and Microengineering 23:045004.[http://dx.doi.org/10.1088/0960-1317/23/4/045004] We apply an interpolation-based edge-tracking algorithm to measure nanoscale displacements of microdevices, and further enhance its ability to reject noisy signals using averaging of multiple image frames. We present…

M. De Volder, A.J. Hart. Engineering hierarchical nanostructures by elastocapillary self-assembly. Angewandte Chemie 52:2412–2425, 2013. [http://dx.doi.org/10.1002/anie.201205944] Surfaces coated with nanoscale filaments such as silicon nanowires and carbon nanotubes are potentially compelling for high-performance battery and capacitor electrodes, photovoltaics, electrical interconnects, substrates for engineered cell growth, dry adhesives, and other smart materials. However, many of these…