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Developing theranostic devices to detect bleeding and effectively control hemorrhage in the prehospital setting is an unmet medical need. Herein, an all‐in‐one theranostic platform is presented, which is constructed by sandwiching silk fibroin (SF) between two silver nanowire (AgNW) based conductive electrodes to non‐enzymatically diagnose local bleeding and stop the hemorrhage at the wound site. Taking advantage of the hemostatic property of natural SF, the device is composed of a shape‐memory SF sponge, facilitating blood clotting, with ≈82% reduction in hemostatic time in vitro as compared with untreated blood. Furthermore, this sandwiched platform serves as a capacitive sensor that can detect bleeding and differentiate between blood and other body fluids (i.e., serum and water) via capacitance change. In addition, the AgNW electrode endows anti‐infection efficiency against Escherichia coli and Staphylococcus aureus. Also, the device shows excellent biocompatibility and gradually biodegrades in vivo with no major local or systemic inflammatory responses. More importantly, the theranostic platform presents considerable hemostatic efficacy comparable with a commercial hemostat, Dengen, in rat liver bleeding models. The theranostic platform provides an unexplored strategy for the intelligent management of hemorrhage, with the potential to significantly improve patients' well‐being through the integration of diagnostic and therapeutic capabilities. [ABSTRACT FROM AUTHOR]

Exosomes, a form of small extracellular vesicles, play a crucial role in the metastasis of cancers and thus are investigated as potential biomarkers for cancer diagnosis. However, conventional detection methods like immune‐based assay and microRNA analyses are expensive and require tedious pretreatments and lengthy analysis time. Since exosomes related to cancers are reported to exist in tears, a poly(2‐hydroxyethyl methacrylate) contact lens embedded with antibody‐conjugated signaling microchambers (ACSM‐PCL) capable of detecting tear exosomes is reported. The ACSM‐PCL exhibits high optical transparency and mechanical properties, along with extraordinary biocompatibility and good sensitivity to exosomes. A gold nanoparticle colorimetric assay is employed to visualize captured exosomes. The ACSM‐PCL can detect exosomes in the pH range of 6.5–7.4 (similar to the human tear pH) and have a strong recovery yield in bovine serum albumin solutions. In particular, the ACSM‐PCL can detect exosomes in various solutions, including regular buffer, cell culture media from various cell lines, and human tears. Finally, the ACSM‐PCL can differentiate expression of exosome surface proteins hypothesized as cancer biomarkers. With these encouraging results, this ACSM‐PCL is promised to be the next generation smart contact lens as an easy‐to‐use, rapid, noninvasive monitoring platform of cancer pre‐screening and supportive diagnosis. [ABSTRACT FROM AUTHOR]

The nonlinear torque-voltage characteristics in two-terminal electrostatic actuators can be utilized to magnify the torque generated by a drive voltage applied to one electrode if a fixed dc bias is applied to the other. The resulting torque is enhanced by torque gain factor [G.sub.r] > 1, and the drive voltage is effectively multiplied by voltage gain factor [G.sub.v] > 1 compared to that of an actuator with no dc bias. These gain factors are generated at the expense of a reduced stable range. In this paper, we study and determine experimentally the tradeoff between torque and voltage gains versus stable range for one-dimensional (1-D), three-terminal, parallel-plate angular electrostatic actuators under dc bias. Simple approximate analytical relations are derived for voltage and torque gain as functions of applied dc bias voltage. We demonstrate that for voltage gains of 2-4, the angular range is marginally reduced. Index Terms--Electrostatic actuators, micromirror, parallel-plate, torque magnification.

This paper presents the design, fabrication, and testing of a two-axis 320 pixel micromirror array. The mirror platform is constructed entirely of single-crystal silicon (SCS) minimizing residual and thermal stresses. The 14-[micro]m-thick rectangular (750 x 800 [micro][m.sup.2]) silicon platform is coated with a 0.1-[micro]m-thick metallic (Au) reflector. The mirrors are actuated electrostatically with shaped parallel plate electrodes with 86 [micro]m gaps. Large area 320-mirror arrays with fabrication yields of 90% per array have been fabricated using a combination of bulk micromachining of SOI wafers, anodic bonding, deep reactive ion etching, and surface micromachining. Several type of micromirror devices have been fabricated with rectangular and triangular electrodes. Triangular electrode devices displayed stable operation within a ([+ or -] 5[degress], [+ or -] 5[degrees]) (mechanical) angular range with voltage drives as low as 60 V. Index Terms--Al etching, deep-reactive ion etching (DRIE), micromirrors, optical switching, silicon on insulator (SOD wafers.

This paper presents a linear array of tilting mirrors used to attenuate the various wavelengths in a DWDM optical signal. Attenuation of 21 dB at snap-down was achieved by the tilting mirrors, substituting for a liquid crystal spatial light modulator (SLM) in a commercial dynamic spectral equalizer (DSE). Linear fill factor of 92% was achieved, allowing closely spaced wavelength channels to be individually attenuated. A two layer polysilicon process with a thick epi-poly mirror was used to fabricate the SLM. Initial mirrors had a radius of curvature of 25 cm. A novel accelerated HF-[H.sub.2]S[O.sub.4] etch allowed 100/[micro]m wide mirrors to be undercut in 12 min with no etch release holes. [1101] Index Terms--optical dynamic spectrum equalizer (DSE), epipoly, HF release, mirror array, spatial light modulator (SLM).

Wearable piezoresistive sensors are being developed as electronic skins (E‐skin) for broad applications in human physiological monitoring and soft robotics. Tactile sensors with sufficient sensitivities, durability, and large dynamic ranges are required to replicate this critical component of the somatosensory system. Multiple micro/nanostructures, materials, and sensing modalities have been reported to address this need. However, a trade‐off arises between device performance and device complexity. Inspired by the microstructure of the spinosum at the dermo epidermal junction in skin, a low‐cost, scalable, and high‐performance piezoresistive sensor is developed with high sensitivity (0.144 kPa‐1), extensive sensing range (0.1–15 kPa), fast response time (less than 150 ms), and excellent long‐term stability (over 1000 cycles). Furthermore, the piezoresistive functionality of the device is realized via a flexible transparent electrode (FTE) using a highly stable reduced graphene oxide self‐wrapped copper nanowire network. The developed nanowire‐based spinosum microstructured FTEs are amenable to wearable electronics applications. [ABSTRACT FROM AUTHOR]

Irregular hemodynamics affects the progression of various vascular diseases, such atherosclerosis or aneurysms. Despite the extensive hemodynamics studies on animal models, the inter-species differences between humans and animals hamper the translation of such findings. Recent advances in vascular tissue engineering and the suitability of in vitro models for interim analysis have increased the use of in vitro human vascular tissue models. Although the effect of flow on endothelial cell (EC) pathophysiology and EC-flow interactions have been vastly studied in two-dimensional systems, they cannot be used to understand the effect of other micro- and macro-environmental parameters associated with vessel wall diseases. To generate an ideal in vitro model of the vascular system, essential criteria should be included: 1) the presence of smooth muscle cells or perivascular cells underneath an EC monolayer, 2) an elastic mechanical response of tissue to pulsatile flow pressure, 3) flow conditions that accurately mimic the hemodynamics of diseases, and 4) geometrical features required for pathophysiological flow. In this paper, we review currently available in vitro models that include flow dynamics and discuss studies that have tried to address the criteria mentioned above. Finally, we critically review in vitro fluidic models of atherosclerosis, aneurysm, and thrombosis. [ABSTRACT FROM AUTHOR]

Wearable and implantable pressure sensors are in great demand for personalized health monitoring. Pressure sensors with low operation voltage and low power-consumption are desired for energy-saving devices. Organic iontronic devices, such as organic electrochemical transistors (OECTs), have demonstrated great potential for low power-consumption bioelectronic sensing applications. The ability to conduct both electrons and ions, in addition to their low-operation voltage has enabled the widespread use of OECTs in different biosensing fields. However, despite these merits, OECTs have not been demonstrated for pressure sensing applications. This is because most OECTs are gated with aqueous electrolyte, which fails to respond to external pressure. Here, a low power-consumption iontronic pressure sensor is presented based on an OECT, in which an ionic hydrogel is used as a solid gating medium. The resultant iontronic device operated at voltages less than 1 V, with a power-consumption between ~ 101– $10^{3} \mu \text{W}$ , while maintaining a tunable sensitivity between 1 ~ 10 kPa−1. This work places OECTs on the frontline for developing low power-consumption iontronic pressure sensors and for biosensing applications. [ABSTRACT FROM AUTHOR]

Abstract Background Potential routes of nanomaterial exposure include inhalation, dermal contact, and ingestion. Toxicology of inhalation of ultra-fine particles has been extensively studied; however, risks of nanomaterial exposure via ingestion are currently almost unknown. Using enterocyte-like Caco-2 cells as a small intestine epithelial model, the possible toxicity of CdSe quantum dot (QD) exposure via ingestion was investigated. Effect of simulated gastric fluid treatment on CdSe QD cytotoxicity was also studied. Results Commercially available CdSe QDs, which have a ZnS shell and poly-ethylene glycol (PEG) coating, and in-house prepared surfactant coated CdSe QDs were dosed to Caco-2 cells. Cell viability and attachment were studied after 24 hours of incubation. It was found that cytotoxicity of CdSe QDs was modulated by surface coating, as PEG coated CdSe QDs had less of an effect on Caco-2 cell viability and attachment. Acid treatment increased the toxicity of PEG coated QDs, most likely due to damage or removal of the surface coating and exposure of CdSe core material. Incubation with un-dialyzed in-house prepared CdSe QD preparations, which contained an excess amount of free Cd2+, resulted in dramatically reduced cell viability. Conclusion Exposure to CdSe QDs resulted in cultured intestinal cell detachment and death; cytotoxicity depended largely, however, on the QD coating and treatment (e.g. acid treatment, dialysis). Experimental results generally indicated that Caco-2 cell viability correlated with concentration of free Cd2+ ions present in cell culture medium. Exposure to low (gastric) pH affected cytotoxicity of CdSe QDs, indicating that route of exposure may be an important factor in QD cytotoxicity.

Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques. Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels that are used in commercial contact lenses with a three-dimensional (3D) printed mold. We investigated the corresponding capillary flow behaviors in these microchannels. We observed different capillary flow regimes in these microchannels, depending on their hydration level. In particular, we found that a peristaltic pressure could reinstate flow in a dehydrated channel, indicating that the motion of eye-blinking may help tears flow in a microchannel-containing contact lens. Colorimetric pH and electrochemical Na+ sensing capabilities were demonstrated in these microchannels. This work paves the way for the development of microengineered poly(HEMA) hydrogels for various biomedical applications such as eye-care and wearable biosensing. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have been widely used for regenerative therapy. In most current clinical applications, MSCs are delivered by injection but face significant issues with cell viability and penetration into the target tissue due to a limited migration capacity. Some therapies have attempted to improve MSC stability by their encapsulation within biomaterials; however, these treatments still require an enormous number of cells to achieve therapeutic efficacy due to low efficiency. Additionally, while local injection allows for targeted delivery, injections with conventional syringes are highly invasive. Due to the challenges associated with stem cell delivery, a local and minimally invasive approach with high efficiency and improved cell viability is highly desired. In this study, a detachable hybrid microneedle depot (d‐HMND) for cell delivery is presented. The system consists of an array of microneedles with an outer poly(lactic‐co‐glycolic) acid shell and an internal gelatin methacryloyl (GelMA)‐MSC mixture (GMM). The GMM is characterized and optimized for cell viability and mechanical strength of the d‐HMND required to penetrate mouse skin tissue is also determined. MSC viability and function within the d‐HMND is characterized in vitro and the regenerative efficacy of the d‐HMND is demonstrated in vivo using a mouse skin wound model. [ABSTRACT FROM AUTHOR]

The use of conducting polymers such as poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) for the development of soft organic bioelectronic devices, such as organic electrochemical transistors (OECTs), is rapidly increasing. However, directly manipulating conducting polymer thin films on soft substrates remains challenging, which hinders the development of conformable organic bioelectronic devices. A facile transfer‐printing of conducting polymer thin films from conventional rigid substrates to flexible substrates offers an alternative solution. In this work, it is reported that PEDOT:PSS thin films on glass substrates, once mixed with surfactants, can be delaminated with hydrogels and thereafter be transferred to soft substrates without any further treatments. The proposed method allows easy, fast, and reliable transferring of patterned PEDOT:PSS thin films from glass substrates onto various soft substrates, facilitating their application in soft organic bioelectronics. By taking advantage of this method, skin‐attachable tattoo‐OECTs are demonstrated, relevant for conformable, imperceptible, and wearable organic biosensing. [ABSTRACT FROM AUTHOR]

A new method is used for characterizing adhesion of monolayered/multilayered graphene sheets on silicon wafer. Local adhesion strength is obtained by measuring the particle height and blister radius by using a scanning electron microscope.