Overcoming the trade-offs among power consumption, fabrication cost, and signal amplification has been a long-standing issue for wearable electronics. We report a high-gain, fully inkjet-printed Schottky barrier organic thin-film transistor amplifier circuit. The transistor signal amplification efficiency is 38.2 siemens per ampere, which is near the theoretical thermionic limit, with an ultralow power consumption of <1 nanowatt. The use of a Schottky barrier for the source gave the transistor geometry-independent electrical characteristics and accommodated the large dimensional variation in inkjet-printed features. These transistors exhibited good reliability with negligible threshold-voltage shift. We demonstrated this capability with an ultralow-power high-gain amplifier for the detection of electrophysiological signals and showed a signal-to-noise ratio of >60 decibels and noise voltage of <0.3 microvolt per hertz1/2at 100 hertz.

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This work describes a rational approach of hydroxyapatite (HAp) nanosurface modification for graft polymerization of -caprolactone (CL). The ring-opening polymerization of CL on HAp surfaces was carried out using three types of HAp with different surface hydroxyl functionality: unmodified HAp (surface OH), HAp modified with L-lactic acid (secondary OH), and HAp modified with ethylene glycol (primary OH). The grafting efficiency and the amount of grafted poly( -caprolactone) (PCL) were dependent on the nature and steric environment of the hydroxyl groups on the HAp surfaces. Transmission electron microscopy measurements and time-dependent phase monitoring indicated that surface-modified HAp could be more uniformly dispersed in methylene chloride than unmodified HAp, and its colloidal stability increased dramatically as the amount of grafted PCL increased. The nanocomposites of PCL and PCL-grafted HAp showed enhanced tensile strength and toughness, compared with that of unmodified HAp and PCL. Increased interfacial interaction parameters (B σy ) for the composite of PCL and PCLgrafted HAp strongly supported the enhanced mechanical strength of the nanocomposites. The use of HAp modified with a larger amount of PCL was found to be much more effective in improving mechanical properties of the nanocomposites.

We report herein the design of a light-responsive gatekeeper for smart nitric oxide (NO) delivery. The gatekeeper is composed of a pH-jump reagent as an intermediary of stimulus and a calcium phosphate (CaP) coating as a shielding layer for NO release. The light irradiation and subsequent acid generation are used as triggers for uncapping the gatekeeper and releasing NO. The acids generated from a light-activated pH-jump agent loaded in the mesoporous nanoparticles accelerated the degradation of the CaP-coating layers on the nanoparticles, facilitating the light-responsive NO release from diazeniumdiolate by exposing a NO donor to physiological conditions. Using the combination of the pH-jump reagent and CaP coating, we successfully developed a light-responsive gatekeeper system for spatiotemporal-controlled NO delivery.