Search

Inorganic material‐based devices are well known for their high performance, excellent stability, and hence suitability for fast computation and communication. But their nonflexibility and nonstretchability often hinder their application in several emerging areas where conformability with irregular 3D surfaces is required in addition to the high performance. Herein, with honeycomb like patterns, the omnidirectional stretchability and conformability of inorganic material‐based device are demonstrated without sacrificing the performance. The simple method presented here facilitates the transfer of patterned inorganic material‐based devices from rigid poly(methyl methacrylate) (PMMA)/glass substrate onto flexible/stretchable substrate such as polydimethylsiloxane simply by placing a water droplet at the PMMA/glass interface. As a proof of concept, the intrinsically brittle indium–gallium–zinc oxide (IGZO)‐based stretchable photodetector devices are fabricated. These devices can be stretched up to 10% without performance degradation, which is a significant improvement considering the less than ≈1% fracture limit of IGZO. With Au decoration, these devices show 127‐fold higher responsivity (295.3 mA W−1) than planar IGZO devices. The higher fracture strain together with the omnidirectional stretchability underpinned by the honeycomb pattern could allow presented devices to conform to complex hemispherical surfaces such as the human eyes, thus showing significant potential for future high‐performance stretchable electronics.

Most of the biological samples such as cells and tissues are phase objects, i.e. absorb little light, resulting in only minor changes in the amplitude of transmitted light through the cell. Since the human eye relies on changes in amplitude of a light wave, cells can be difficult to visualize using a light microscope without a system to enhance cell contrast. One widespread solution is to use dyes that provide molecular specificity. However, involve procedures (fixation) incompatible with live cell imaging. Even labels designed for use with live cell imaging can cause perturbation to normal cellular function and concentrationdependent toxicity effects. Photo-toxicity poses additional barriers to imaging native cell behavior, as the light intensity required to excite a fluorophore can cause cells to behave abnormally or die. Photo-toxicity also adversely affect cell physiology, health, behavior, movement and shape by various mechanisms. Furthermore, label-free techniques enable researchers to avoid the cost of time-intensive dye optimization or stable fluorescentreporter cell line generation. Rather than requiring contrast-enhancing dyes, label-free solutions rely on components of the optical setup that exploit cells inherent contrast mechanisms (thickness and refractive index (RI)) to create image contrast. Abbe theory of image formation phenomenon opened the doors to formulating the problem of contrast precisely like in interferometry. Based on this idea, in the year 1930, Zernike developed phase contrast microscopy (PCM). In the PCM, the contrast is generated by introducing  2 or 3 2 rad into the scattered light from the sample. The PCM technique is a major advancement in the intrinsic contrast imaging, as it reveals inner details of transparent structures without staining or tagging. However, the PCM technique is plagued with significant artifacts such as the halos in the images. In addition to the above PCM technique, there exists other techniques that can also provide the intrinsic contrast from the phase objects, such as dark-field microscopy and Nomarski differential interference contrast microscopy (DIC). The above mentioned techniques are primarily successful in providing a qualitative visualization of phase, however, a quantitative estimation of phase is not feasible.

Most living cells are optically transparent which makes it difficult to visualize them under bright field microscopy. Use of contrast agents or markers and staining procedures are often followed to observe these cells. However, most of these staining agents are toxic and not applicable for live cell imaging. In the last decade, quantitative phase imaging has become an indispensable tool for morphological characterization of the phase objects without any markers. In this paper, we report noninterferometric quantitative phase imaging of live sperm cells by solving transport of intensity equations with recorded intensity measurements along optical axis on a commercial bright field microscope. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.