Micro "Hyper-Channels" on Laser-Refined Cellulose Structures.

Controlled liquid transportation is widely applied in both academia and industry. However, liquid transport applications are limited by parameters such as driving forces, precision, and velocity. Herein, a simple laser-refining technology is presented to produce micro "hyper-channels". A cellulose substrate is rendered hydrophobic through silanization and refined with a laser to produce both hierarchical nanostructures and a wettability contrast simultaneously. Such a method enables faster ("hyper"-channel) aqueous liquid transportation (≈25X, 50 mm s-1 ) compared to conventional methods. Complex patterns can be readily produced at different scales with spatial resolution as low as 50 µm. This technique also controls the refining depth on the thin paper substrate. Shallow channels can be fabricated on thin paper substrates that enable fluidic channel-crossover without liquid mixing. With certain parameters, the technique creates "portals" through the substrate, allowing trans-dimensional liquid transportation between two layers of a single sheet of substrate. The fluid throughput can be increased, while also permitting fluidic channel crossover without liquid mixing. By introducing multiple portals, the controlled fluid can transfer trans-dimensionally several times, enabling further fluidic complexity. The real-life utility of the method is demonstrated by creating a trans-dimensional microfluidic device for colorimetric detection.

Realizing new designs of multiplexed electrode chips by 3-D printed masks.

Creating small and portable analytical methods is a fast-growing field of research. Devices capable of performing bio-analytical detection are especially desirable with the onset of the global pandemic. Lab-on-a-chip (LOC) technologies, including rapid point-of-care (POC) devices such as glucose sensors, are attractive for applications in resource-poor settings. There are many challenges in creating such devices, from sensitive molecular designs to stable conditions for storing the sensor chips. In this study we have explored using three-dimensional (3D) printing to create shadow masks as a low-cost method to produce multiplexed electrodes by physical vapour deposition. Although the dimensional resolution of the electrodes produced by using 3D printed masks is inferior to those made through photolithography-based techniques, their dimensions can be readily tailored ranging from 1 mm to 3 mm. Multiple mask materials were tested, such as polylactic acid and polyethylene terephthalate glycol, with acrylonitrile butadiene styrene shown to be the best. Simple strategies in making chip holders by 3D printing and controlling working electrode surface area with epoxy glue were also investigated. The prepared chips were tested by performing surface chemistry with thiol-containing molecules and monitoring the signals electrochemically.

Facile Actuation of Organic and Aqueous Droplets on Slippery Liquid-Infused Porous Surfaces for the Application of On-Chip Polymer Synthesis and Liquid-Liquid Extraction.

Digital microfluidics employs water-repellant surfaces to exquisitely manipulate droplets of water for chemical analysis. However, the actuation and manipulation of organic droplets is still relatively unexplored as it is significantly more difficult to synthesize organic-repellent surfaces compared to water-repellent surfaces. Here, we present the fabrication of slippery liquid-infused porous surfaces (SLIPS) based on a porous polymer monolithic approach. The synthesized SLIPS were able to repel organic liquids such as hexane and methanol with a contact angle of 42.1 ± 0.4° and 69.0 ± 1.8°, respectively, as well as water with a contact angle of 115.8 ± 0.8°. More importantly for digital microfluidic applications, the sliding angle of liquids tested was between 4° and 6°. As a result, droplets containing magnetically susceptible material could be facilely manipulated on the SLIPS surface. A systematic actuation study was carried out to explore how actuation parameters including speed, paramagnetic particle (PMP) concentrations, and droplet volume impacted the outcomes (droplet actuation, disengagement, and PMP extraction). Two different applications were used to demonstrate the utility of actuating organic droplets on SLIPS surfaces including on-chip liquid-liquid extractions of natural products (NPs) from marine bacteria and droplet-based polymer synthesis with different polymerization conditions. Both applications employ an aqueous droplet and organic droplet interface at which either phase transfer or a chemical reaction is carried out. Two NPs (prodigiosin from Pseudoalteromonas rubra and violacein from Pseudoalteromonas luteoviolacea) were extracted, from aqueous droplets containing the bacteria, into butanol droplets and characterized with matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). Nylon 6,6 was synthesized on-chip via magnetic actuation of organic droplets containing adipoyl chloride and hexamethylamine. Relative intensities of the characteristic polymer masses suggest that droplet-based microfluidic synthesis on slips can be used to probe reaction conditions. The compatibility of SLIPS with both aqueous and organic solutions opens up a wider number of droplet-based sample preparation protocols and chemical transformations.

Pain flashbacks in posttraumatic stress disorder.

OBJECTIVES: Surgical patients who regain consciousness while under general anesthesia may develop symptoms of Posttraumatic Stress Disorder (PTSD). One common PTSD symptom is the experiencing of abnormal perceptions during which the patient feels as if the trauma is recurring. The objective of this report is to document the re-occurrence of pain as part of the PTSD sequelae. RESULTS: We present two patients who developed PTSD following an episode of awareness under anesthesia. In both cases, posttraumatic sequelae persisted for years and included pain symptoms that resembled, in quality and location, pain experienced during surgery. In addition to their similarity to the original pain, these pain symptoms were triggered by stimuli associated with the traumatic situation, suggesting that they were flashbacks to the episode of awareness under anesthesia. DISCUSSION: The similarity between the patients' pain symptoms and pain experienced during trauma, the triggering by traumatic cues, and the associated emotional arousal and avoidance suggest the involvement of a somatosensory memory mechanism.

Factors associated with refusal to enter a clinical trial: epidural anesthesia is a deterrent to participation.

PURPOSE: To compare patients who participate in a clinical trial for pain management involving epidural anesthesia to those who refuse and document their reasons for refusing. METHODS: Demographic and health history information was collected from 621 female patients who were screened for inclusion in a pain management trial involving epidural anesthesia. Patients who completed the clinical trial (n = 149) were compared to those who consented to provide screening information but did not enter the trial (n = 472). RESULTS: Sixty-seven percent of women who refused cited unwillingness to have an epidural as the reason for their decision. Non-Caucasians (P < 0.01), patients with no history of mood/anxiety disorders (P < 0.016) or systemic disease (P < 0.02), and patients with certain types of pain (P < 0.02) were more likely to refuse to participate in the clinical trial. A longer duration between recruitment and surgery was also found to be associated with higher participation rates (P < 0.01). A logistic regression equation significantly predicted which patients would participate or refuse (P < 0.0001), indicating that a specific set of health and demographic factors strongly influence the decision to participate in a trial. CONCLUSIONS: The decision to participate in a clinical trial is viewed as a risk/benefit analysis. Factors such as short recruitment to surgery intervals and pre-existing pain, which increase the salience of risks associated with the trial, may result in lower participation rates. Overall, epidural anesthesia is a strong deterrent to participation in a clinical trial.