Fabrication of polymeric lenses using magnetic liquid molds

Abstract

Traditional molding and casting processes in optical manufacturing require sophisticated and expensive molds and molding equipment. In this work, magnetic liquid droplets were used as soft and deformable molds. The magnetic drop within an immiscible polymeric resin forms a conical shape at the interface due to the equilibrium of magnetostatic force and surface tension, which results in a plano–concave lens after curing. An apparatus was assembled to control the amplitude and gradient of the magnetic field. A Shack-Hartmann sensor was employed to measure the focal length of the formed polydimethylsiloxane lenses. The effects of magnetic field intensity, gradient of the magnetic field, and magnetic susceptibility were investigated. This technique is low cost, rapid, and straightforward and can be used for forming lenses with different sizes and shapes.

Gravity‐Controlled and Boundary‐Constrained High‐Throughput Fabrication of Polymeric Miniature Lens Arrays

“…In most cases having complex boundaries, the closed‐form solutions for the surface shape is unavailable by solving $$ \delta U=0$$. With respect to the simplest case with constant boundary, namely $$ \rho _{\rm b}=\frac{d_{\rm o}}{2}$$ and $$ z_{\rm o}=H$$, the governing law for the deformed surface can be approximated by the Young–Laplace equation as [ 7 ] $$\begin{equation} \gamma {\left(\frac{1}{r_x} +\frac{1}{r_y} \right)}=\Delta P \end{equation}$$where $$ r_x$$ and $$ r_y$$ are the principle radii of the lens curvature, and the pressure difference $$ \Delta P$$ can be roughly estimated as $$ \Delta P=\rho _{\rm m} gH$$ by ignoring the gravity force of the spherical dome.…”

“…Owing to the low cost, low density, and good optical and mechanical property, the polymeric lenses have attracted special attention and been widely applied in ultraviolet and visible optical systems. [ 6,7 ]…”

“…As for the surface wettability modification, for example, the electrically dewetting, [ 22 ] plasma‐based surface treatment [ 18 ] and photomask‐based coating, [ 23 ] are successfully applied to generate lenslets with largely variable focal length and numerical aperture. With respect to the external force‐enabled shape control, the electrostatic force, [ 24 ] magnetic force, [ 7 ] and negative‐pressure [ 25 ] are imposed on the formed lenslet to tune the curvatures. Although the template‐based and capillarity enabled method is a simple and high‐throughput technique for the fast generation of MLAs, the curvature control greatly depends on extra‐operations, which requires excessive procedures and expensive facilities.…”

Smart polymers and nanocomposites for 3D and 4D printing

“…Tunable and rapid remote actuation in different applications such as biological systems is highly favored. Magnetic stimuli can be used to temporally and spatially control the shapeshifting through a physical non-invasive process and without material phase change [172]. Zhu et al [173] fabricated magnetically responsive 3D structures using a direct writing process which presented a quick response time to an external magnetic field.…”

Predictive mechanics-based model for depth of cut (DOC) of waterjet in soft tissue for waterjet-assisted medical applications

“…Because of the mentioned di culties in common tissue mimicking simulants, we have used Poly (styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS), Kraton Polymers LLC (G1650, and G1652, Houston, TX, USA) as the main material for our tissue-mimicking simulants [36], [19], and [20]. The solvent used for SEBS is light mineral oil, which makes it a more environmentally stable substitute for water-based hydrogels.…”