The integration of fully printed transistors on low cost paper substrates compatible with roll‐to‐roll processes is demonstrated here. Printed electronics promises to enable a range of technologies ...on paper including printed sensors, RF tags, and displays. However, progress has been slow due to the paper roughness and ink absorption. This is solved here by employing gravure printing to print local smoothing pads that also act as an absorption barrier. This innovative local smoothing process retains desirable paper properties such as foldability, breathability, and biodegradability outside of electronically active areas. Atomic force microscopy measurements show significant improvements in roughness. The polymer ink and printing parameters are optimized to minimize ink absorption and printing artifacts when printing the smoothing layer. Organic thin film transistors (OTFT) are fabricated on top of this locally smoothed paper. OTFTs exhibit performance on par with previously reported printed transistors on plastic utilizing the same materials system (pBTTT semiconductor, poly‐4‐vinylphenol dielectric). OTFTs deliver saturation mobility approaching 0.1 cm2V–1s–1 and on‐off‐ratio of 3.2 × 104. This attests to the quality of the local smoothing, and points to a promising path for realizing electronics on paper.
Fully printed transistors are demonstrated on paper substrates with performance on par with plastic based devices. Desirable paper properties such as foldability, breathability, and biodegradability are preserved outside of electronically active areas by an innovative locally printed smoothing process. This process is fully compatible with existing paper packaging process flows.
Bioelectronic interfaces require electrodes that are mechanically flexible and chemically inert. Flexibility allows pristine electrode contact to skin and tissue, and chemical inertness prevents ...electrodes from reacting with biological fluids and living tissues. Therefore, flexible gold electrodes are ideal for bioimpedance and biopotential measurements such as bioimpedance tomography, electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG). However, a manufacturing process to fabricate gold electrode arrays on plastic substrates is still elusive. In this work, a fabrication and low‐temperature sintering (≈200 °C) technique is demonstrated to fabricate gold electrodes. At low‐temperature sintering conditions, lines of different widths demonstrate different sintering speeds. Therefore, the sintering condition is targeted toward the widest feature in the design layout. Manufactured electrodes show minimum feature size of 62 μm and conductivity values of 5 × 10 6 S m−1. Utilizing the versatility of printing and plastic electronic processes, electrode arrays consisting of 31 electrodes with electrode‐to‐electrode spacing ranging from 2 to 7 mm are fabricated and used for impedance mapping of conformal surfaces at 15 kHz. Overall, the fabrication process of an inkjet‐printed gold electrode array that is electrically reproducible, mechanically robust, and promising for bioimpedance and biopotential measurements is demonstrated.
Fabrication of inkjet‐printed flexible gold electrode arrays on plastic substrates is described, with a special focus on laser‐cut freestanding electrodes, low‐temperature sintering, and the methodology used for impedance mapping on conformal surfaces. Taking advantage of low‐cost and large‐area manufacturing techniques, these electrically reproducible and mechanically robust electrode arrays are promising for novel wearable biomedical sensing.
This work employs novel SnO2 gel‐like precursors in conjunction with sol–gel deposited ZrO2 gate dielectrics to realize high‐performance transparent transistors. Representative devices show excellent ...performance and transparency, and deliver mobility of 103 cm2 V−1 s−1 in saturation at operation voltages as low as 2 V, a sub‐threshold swing of only 0.3 V/decade, and Ion/Ioff of 104∼105.
We investigated the effect of PbSe quantum dot size on the performance of Schottky solar cells made in an ITO/PEDOT/PbSe/aluminum structure, varying the PbSe nanoparticle diameter from 1 to 3 nm. In ...this highly confined regime, we find that the larger particle bandgap can lead to higher open-circuit voltages (∼0.6 V), and thus an increase in overall efficiency compared to previously reported devices of this structure. To carry out this study, we modified existing synthesis methods to obtain ultrasmall PbSe nanocrystals with diameters as small as 1 nm, where the nanocrystal size is controlled by adjusting the growth temperature. As expected, we find that photocurrent decreases with size due to reduced absorption and increased recombination, but we also find that the open-circuit voltage begins to decrease for particles with diameters smaller than 2 nm, most likely due to reduced collection efficiency. Owing to this effect, we find peak performance for devices made with PbSe dots with a first exciton energy of ∼1.6 eV (2.3 nm diameter), with a typical efficiency of 3.5%, and a champion device efficiency of 4.57%. Comparing the external quantum efficiency of our devices to an optical model reveals that the photocurrent is also strongly affected by the coherent interference in the thin film due to Fabry-Pérot cavity modes within the PbSe layer. Our results demonstrate that even in this simple device architecture, fine-tuning of the nanoparticle size can lead to substantial improvements in efficiency.
Transparent microelectrodes that facilitate simultaneous optical and electrophysiological interfacing are desirable tools for neuroscience. Electrodes made from transparent conductors such as ...graphene and indium tin oxide (ITO) show promise but are often limited by poor charge‐transfer properties. Herein, microelectrodes are demonstrated that take advantage of the transparency and volumetric capacitance of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Ring‐shaped microelectrodes are fabricated by inkjet‐printing PEDOT:PSS, encapsulating with Parylene C, and then exposing a contact site that is much smaller than the microelectrode outer diameter. This unique structure allows the encapsulated portion of the microelectrode volume surrounding the contact site to participate in signal transduction, which reduces impedance and enhances charge storage capacity. While using the same 100 μm diameter contact site, increasing the outer diameter of the encapsulated electrode from 300 to 550 μm reduces the impedance from 294 ± 21 to 98 ± 2 kΩ, respectively, at 1 Hz. Similarly, the charge storage capacity is enhanced from 6 to 21 mC cm−2. The PEDOT:PSS microelectrodes provide a low‐haze, high‐transmittance optical interface, demonstrating their suitability for optical neuroscience applications. They remain functional after a million 1 V stimulation cycles, up to 600 μA of stimulation current, and more than 1000 mechanical bending cycles.
Inkjet‐printed transparent microelectrodes composed of a mixed‐conductor polyelectrolyte are demonstrated and characterized according to their electrochemical, optical, and mechanical properties. It is shown that the impedance and charge storage capacity of these microelectrodes can be improved by increasing the volume of the microelectrode without altering the contact site area or the transparency.
An isogenic hiPSC-derived BBB-on-a-chip Motallebnejad, Pedram; Thomas, Andrew; Swisher, Sarah L. ...
Biomicrofluidics,
11/2019, Letnik:
13, Številka:
6
Journal Article
Recenzirano
Odprti dostop
The blood-brain barrier (BBB) is composed of brain microvascular endothelial cells (BMECs) that regulate brain homeostasis, and astrocytes within the brain are involved in the maintenance of the BBB ...or modulation of its integrity in disease states via secreted factors. A major challenge in modeling the normal or diseased BBB is that conventional in vitro models lack either the physiological complexity of the BBB or key functional features such as formation of a sufficiently tight barrier. In this study, we utilized human induced pluripotent stem cell (hiPSC)-derived BMECs in a BBB-on-a-chip device that supports flow and coculture with an astrocyte-laden 3D hydrogel. The BMECs are separated from the hydrogel by a porous membrane with either 0.4 or 8.0 μm pore size, making the device suitable for studying the transport of molecules or cells, respectively, across the BBB. In addition, all cells seeded in the device are differentiated from the same hiPSC line, which could enable genetic and rare disease modeling. Formation of a confluent BMEC barrier was confirmed by immunocytochemistry of tight junction proteins and measurement of fluorescein permeability. Integrity of the barrier was further assessed by performing impedance spectroscopy in the device. Finally, the ability of this device to recapitulate a disease model of BBB disruption was demonstrated, with apical addition of TGF-β1 leading to transendothelial electrical resistance reduction and indicators of astrocyte activation. These results demonstrate the utility of the fabricated device for a broad range of applications such as drug screening and mechanistic studies of BBB disruption.
Transparent microelectrodes that facilitate simultaneous optical and electrophysiological interfacing are desirable tools for neuroscience. Electrodes made from transparent conductors such as ...graphene and indium tin oxide (ITO) show promise but are often limited by poor interfacial charge-transfer properties. Here, microelectrodes are demonstrated that take advantage of the transparency and volumetric capacitance of the mixed ion-electron conductor Poly(3,4- ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Ring-shaped microelectrodes are fabricated by inkjet-printing PEDOT:PSS, encapsulating with Parylene-C, and then exposing a contact site that is much smaller than the microelectrode outer diameter. This unique structure allows the encapsulated portion of the microelectrode volume surrounding the contact site to participate in signal transduction, which reduces impedance and enhances charge storage capacity. While using the same 100 μm diameter contact site, increasing the outer diameter of the encapsulated electrode from 300 to 550 μm reduces the impedance from 294±21 to 98±2 kΩ, respectively, at 1 Hz. Similarly, the charge storage capacity is enhanced from 6 to 21 mC cm
−2
. The PEDOT:PSS microelectrodes provide a low-haze, high-transmittance optical interface, demonstrating their suitability for optical neuroscience applications. They remain functional after a million 1 V stimulation cycles, up to 600 μA of stimulation current, and more than 1000 mechanical bending cycles.
Inkjet-printed transparent microelectrodes composed of a mixed-conductor polyelectrolyte are demonstrated and characterized according to their electrochemical, optical, and mechanical properties. It is shown that the impedance and charge storage capacity of these microelectrodes can be improved by increasing the volume of the microelectrode without altering the contact site area or the transparency.
When pressure is applied to a localized area of the body for an extended time, the resulting loss of blood flow and subsequent reperfusion to the tissue causes cell death and a pressure ulcer ...develops. Preventing pressure ulcers is challenging because the combination of pressure and time that results in tissue damage varies widely between patients, and the underlying damage is often severe by the time a surface wound becomes visible. Currently, no method exists to detect early tissue damage and enable intervention. Here we demonstrate a flexible, electronic device that non-invasively maps pressure-induced tissue damage, even when such damage cannot be visually observed. Using impedance spectroscopy across flexible electrode arrays in vivo on a rat model, we find that impedance is robustly correlated with tissue health across multiple animals and wound types. Our results demonstrate the feasibility of an automated, non-invasive 'smart bandage' for early detection of pressure ulcers.
Paravertebral nerve blocks (PVBs) are frequently used to treat pain during and following breast surgery, but have various undesirable risks such as pneumothorax. The erector spinae plane block (ESPB) ...also provides perioperative breast analgesia, but is purported to be easier to administer with a favorable safety profile. However, it remains unknown if the new ESPB provides comparable analgesia as the decades-old PVB technique.
Subjects undergoing unilateral or bilateral non-mastectomy breast surgery were randomized to a single-injection ESPB or PVB in a subject-blinded fashion (ropivacaine 0.5% with epinephrine; 20 mL unilateral or 16 mL/side for bilateral). We hypothesized that (1) analgesia would be non-inferior in the recovery room as measured on a Numeric Rating Scale (NRS) with ESPB, and (2) opioid consumption would be non-inferior in the operating and recovery rooms with ESPB.
Both pain scores and opioid consumption were higher in subjects with ESPBs (n=50) than PVBs (n=50; median NRS 3.0 vs 0; 95% CI -3.0 to 0; p=0.0011; and median morphine equivalents 2.0 vs 1.5 mg; 95% CI -1.2 to -0.1; p=0.0043). No block-related adverse events occurred in either group.
PVBs provided superior analgesia and reduced opioid requirements following non-mastectomy breast surgery. To compare the relatively rare complications between the techniques will require a sample size 1-2 orders of magnitude greater than the current investigation; however, without a dramatic improvement in safety profile for ESPBs, it appears that PVBs are superior to ESPBs for postoperative analgesia after non-mastectomy breast surgery.
NCT03549234.
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