Large‐Area, Selective Transfer of Microstructured Silicon: A Printing‐ Based Approach to High‐Performance Thin‐Film Transistors Supported on Flexible Substrates

Abstract

the protein adsorption assay, and onto a glass substrate for the cell and platelet adhesion assay. The samples were subsequently heated to 100 C under vacuum for 1 h. It was confirmed by XPS (O/C atomic ratio) that the surface structure of the present sample (heated at 100 C for 1 h) was almost the same as that of the equilibrated sample [8], which was heated at 140 C for 12±24 h.Surface Analysis: The surfaces of the samples were observed using an SEM (XL30, FEI Japan Ltd., Japan), a profile measurement microscope (VF-7500, Keyence Co., Japan), and an XPS (Quantum 2000, Ulvac-Phi Inc., Japan). In the XPS measurements, monochromated Al Ka X-rays were used as the source, and the photoelectron take-off angle was set at 45.Protein Adsorption Assay: The samples were immersed in 2 mL of a phosphate-buffered saline (PBS), supplemented with fibrinogen (40 lg mL ±1 , Sigma-Aldrich, USA) or albumin (460 lg mL ±1 , SigmaAldrich., USA) at 37 C for 2 h. After removal from the saline solution, the samples were gently rinsed with PBS three times, and then dried. The N/C atomic ratio on the sample surface was determined from XPS measurements.Cell Adhesion Assay: The samples were placed in a 24-well PS plate. The L929 cells (Riken Bioresource Center, Japan) were suspended in Dulbecco's modified eagle medium supplemented with 5 % horse serum at a concentration of 1.2 10 5 cells mL ±1. 2 mL of the cell suspensions were added to the samples in each well, and the cells were cultured at 37 C in a 5 % CO 2 atmosphere for 20 h. After cell culturing, the samples were gently rinsed with PBS three times. Cells adhering to the sample surface were detached from the samples using an ethylenediaminetetraacetic acid (EDTA)-trypsin solution, and then stained with trypan blue. The number of stained cells was counted using a hemocytometer.Platelet Adhesion Assay: Blood was collected in a heparin-containing polypropylene tube from a 22-year-old man with his consent. The blood, containing 2 U mL ±1 of heparin, was centrifuged twice at 160 g to obtain platelet-rich plasma. This was then centrifuged at 1300 g for 10 min to separate the platelets from the plasma. The platelets were labeled with 5-or 6-(N-succinimidyloxycarbonyl)-3¢,6¢-O,O¢-diacetylfluorescein at 37 C for 30 min, and then centrifuged at 1300 g for 10 min. The labeled platelets were then suspended in the supernatant fluid separated centrifugally from the platelet-rich plasma at a near physiological concentration of 1.0 10 5 platelets mL ±1 . The samples, PMMA (negative control), and HUVEC (positive control) were subjected to a shear flow of the platelet suspension at a rate of 50 s ±1 using a cone and plate-type viscometer [9] equipped with a microscope and a silicon-intensified target camera. The number of platelets adhering to the sample was counted at 5, 10, and 15 min after imposing the shear flow.

Piezoelectric BaTiO3Thin Film Nanogenerator on Plastic Substrates

“…The BaTiO 3 thin film was then transferred onto a flexible substrate by means of standard microfabrication and soft lithographic printing techniques. [17][18][19][20] To measure the positive and negative output voltage/current signals, we deposited the IDEs on flexible BaTiO 3 . Figure 1a shows a schematic of the fabrication steps.…”

Self-assembled single-crystal silicon circuits on plastic

“…Poor charge carrier mobility in these devices [in comparison, the electron mobility in single-crystal silicon transistors exceeds 1,000 cm 2 ͞V-s (14)] translates to poor frequency response and high power consumption. Some of the best devices demonstrated to date were made by means of a creative approach that uses silicon ribbons released from a wafer and reassembled on a polymer substrate to yield stretchable circuits (15,16). This method has produced circuits with form factors replicating the original silicon wafer (the area and coverage attained are similar to a wafer originally used for processing) and with performance parameters that are affected by strain applied to the substrate.…”

Inorganic semiconductor nanomaterials for flexible and stretchable bio-integrated electronics

“…The mechanically soft nature of the stamp avoids fracture in the NMs during this process. 45,69,[71][72][73][74] An important consideration is in control over the adhesion between nanomaterials and the surfaces of the stamps, in ways that allow switching from strong to weak states for retrieval and printing, respectively. 69,70,75,76 Various approaches, ranging from those that exploit viscoelastic effects 69,75 to interface shear loading 76 to pressureinduced contact modulation, 70,77 can be effective.…”