Here, the fabrication of nonwoven fabric by blow spinning and its application to smart textronics are demonstrated. The blow-spinning system is composed of two parallel concentric fluid streams: i) a polymer dissolved in a volatile solvent and ii) compressed air flowing around the polymer solution. During the jetting process with pressurized air, the solvent evaporates, which results in the deposition of nanofibers in the direction of gas flow. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) dissolved in acetone is blowspun onto target substrate. Conductive nonwoven fabric is also fabricated from a blend of single-walled carbon nanotubes (SWCNTs) and PVdF-HFP. An all-fabric capacitive strain sensor is fabricated by vertically stacking the PVdF-HFP dielectric fabric and the SWCNT/PVdF-HFP conductive fabric. The resulting sensor shows a high gauge factor of over 130 and excellent mechanical durability. The hierarchical morphology of nanofibers enables the development of superhydrophobic fabric and their electrical and thermal conductivities facilitate the application to a wearable heater and a flexible heat-dissipation sheet, respectively. Finally, the conductive nonwoven fabric is successfully applied to the detection of various biosignals. The demonstrated facile and cost-effective fabrication of nonwoven fabric by the blow-spinning technique provides numerous possibilities for further development of technologies ranging from wearable electronics to textronics.

In this study, a pairing of a previously unidentified 3D printing technique and soft materials is introduced in order to achieve not only high‐resolution printed features and flexibility of the 3D‐printed materials, but also its light‐weight and electrical conductivity. Using the developed technique and materials, high‐precision and highly sensitive patient‐specific wearable active or passive devices are fabricated for personalized health monitoring. The fabricated biosensors show low density and substantial flexibility because of 3D microcellular network‐type interconnected conductive materials that are readily printed using an inkjet head. Using high‐resolution 3D scanned body‐shape data, on‐demand personalized wearable sensors made of the 3D‐printed soft and conductive materials are fabricated. These sensors successfully detect both actively changing body strain signals and passively changing signals such as electromyography (EMG), electrodermal activity (EDA), and electroencephalogram EEG. The accurately tailored subject‐specific shape of the developed sensors exhibits higher sensitivity and faster real‐time sensing performances in the monitoring of rapidly changing human body signals. The newly developed 3D printing technique and materials can be widely applied to various types of wearable, flexible, and light‐weight biosensors for use in a variety of inexpensive on‐demand and personalized point‐of‐care diagnostics.

Self-aligned inversion-channel In0.53Ga0.47As metal-oxide-semiconductor field-effect-transistors (MOSFETs) have been fabricated using the gate dielectrics of in-situ directly atomic-layer-deposited (ALD) HfO2 followed by ALD-Al2O3. There were no surface pretreatments and no interfacial passivation/barrier layers prior to the ALD. TiN/Al2O3 (4 nm)/HfO2 (1 nm)/In0.53Ga0.47As/InP MOS capacitors exhibited well-behaved capacitance-voltage characteristics with true inversion behavior, low leakage current densities of ∼10−8 A/cm2 at ±1 MV/cm, and thermodynamic stability at high temperatures. Al2O3 (3 nm)/HfO2 (1 nm)/In0.53Ga0.47As MOSFETs of 1 μm gate length, with 700 °C–800 °C rapid thermal annealing in source/drain activation, have exhibited high extrinsic drain current (ID) of 1.5 mA/μm, transconductance (Gm) of 0.84 mS/μm, ION/IOFF of ∼104, low sub-threshold swing of 103 mV/decade, and field-effect electron mobility of 1100 cm2/V · s. The devices have also achieved very high intrinsic ID and Gm of 2 mA/μm and 1.2 mS/μm, respectively.

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In this study, we fabricated a three-dimensionally assembled architecture made of reduced graphene oxide (rGO) and utilized it as an ultralightweight strain gauge. Building units for the assembly were prepared over the multiscale starting from functionalized GO nanosheets at the nanoscale to microfluidically processed solid-shelled bubbles at the microscale. These GO solid bubbles were elaborately assembled into close-packed 3D structures over the centimeter scale and then reduced by thermal treatment. Thermally reduced rGO assembly of which the internal structure was spontaneously transformed into a closed-cellular structure such as the 3D rhombic dodecahedral honeycomb lattice during thermal reduction could manifest superior elasticity against a strain of 30% by virtue of the hierarchically interconnected network while securing a low density of about 10 mg/cm3 and mechanical robustness, which was then applied as a strain gauge. The strain gauge with a thermally reduced 3D rGO structure exhibited a gauge factor of around 4 and excellent mechanical durability over 250 cycles, suggesting a new pathway for implementing ultralightweight strain-sensitive materials.