Showing papers by "Tingrui Pan published in 2020"

AmbuBox: A Fast-Deployable Low-Cost Ventilator for COVID-19 Emergent Care.

Abstract: We present a low-cost clinically viable ventilator design, AmbuBox, using a controllable pneumatic enclosure and standard manual resuscitators that are readily available (AmbuBag), which can be rapidly deployed during pandemic and mass-casualty events with a minimal set of components to manufacture and assemble. The AmbuBox is designed to address the existing challenges presented in the existing low-cost ventilator designs by offering an easy-to-install and simple-to-operate apparatus while maintaining a long lifespan with high-precision flow control. As an outcome, a mass-producible prototype of the AmbuBox has been devised, characterized, and validated in a bench test setup using a lung simulator. This prototype will be further investigated through clinical testing. Given the potentially urgent need for inexpensive and rapidly deployable ventilators globally, the overall design, operational principle, and device characterization of the AmbuBox system have been described in detail with open access online. Moreover, the fabrication and assembly methods have been incorporated to enable short-term producibility by a generic local manufacturing facility. In addition, a full list of all components used in the AmbuBox has been included to reflect its low-cost nature.

Active-powering pressure-sensing fabric devices

Abstract: Smart flexible sensing devices with high-comfort and self-powered characteristics are essential in the future-generation wearable human-sensing interface. However, most of the current sensing devices cannot work independently and require external power. Here, we introduced for the first time an active-powering pressure-sensing fabric (APPS) device, integrating a soft-matter battery unit with a fabric-based sensing substrate into one flexible device architecture, which offered a comfortable and reliable human-sensing interface with continuous system powering capacity for wearable physiological and activity monitoring. Notably, the APPS fabric demonstrated an open voltage of 1 V, short circuit of 35 mA cm−2 and capacity of 2.6 mA h cm−2. The specifically designed solid neutral hydrogel electrolyte showed high safety and high force-resistance, guaranteeing the stability of the power output under pressure. Moreover, it exhibited the highest sensitivity of 19.6 Ω−1 kPa−1 in a test pressure range (of <300 kPa) and a mechanical response time of 9 ms. For wearable applications, we packaged the APPS fabric into an adhesive bandage format, from which a series of pressure detection demonstrations were successfully implemented without using any power source. In particular, the APPS fabric device could power the whole system by itself for signal detection and wireless data transmission via a Bluetooth or LED. Benefitting from the unique properties of the active powering and its remarkable performance, the APPS device holds an enormous potential for emerging wearable applications, including health monitoring, gesture recognition and motion monitoring.

Digital microfluidic meter-on-chip

Abstract: The accurate monitoring and control of liquid flow at low flow rates have become increasingly important in contemporary biomedical research and industrial monitoring. Inspired by the drop-counting principle implemented in a clinical gravity drip, we propose a novel microfluidic flowmetry technology for polydimethylsiloxane (PDMS)-based conventional microfluidic devices, known as a microfluidic digital meter-on-chip (DMC), to achieve on-chip and localized microflow measurements with ultrahigh precision and a wide tunable range. The DMC technology primarily relies on capillarity, unlike a gravity drip, to induce a characteristic interfacial droplet pinch-off process, from which digital microflowmetry devices can discretize continuous flow into countable transferred liquid units with consistent quantifiable volumes. Enabled by the passive discretization principle and optical transparency, the DMC device requires no external energy input or bulky control equipment, and a non-contact wireless optical detection scheme using a smartphone can be conveniently used as a readout module. Moreover, the DMC technology achieves an ultrahigh flow-to-frequency sensitivity (6.59 Hz (μL min-1)-1) and resolution (droplet transfer volume down to 2.5 nL, nearly two orders of magnitude smaller than in previously reported work, resulting in ultralow flow rates of 1 μL min-1). In addition, the flow rate measurement range covers up to 80 μL min-1 and down to at least 150 nL min-1 (over 100 times lower than reported similar digital flowmetry on the same time scale) using the current device configuration. Benefiting from its simple device architecture and adaptability, the versatile DMC technology can be seamlessly integrated with various microfluidic and nanofluidic devices for drug delivery and biochemical analysis, serving as a promising technology platform for next-generation highly demanding microflow measurements.

Optimization of Electrical Stimulation for Safe and Effective Guidance of Human Cells.

Abstract: Direct current (DC) electrical stimulation has been shown to have remarkable effects on regulating cell behaviors. Translation of this technology to clinical uses, however, has to overcome several obstacles, including Joule heat production, changes in pH and ion concentration, and electrode products that are detrimental to cells. Application of DC voltages in thick tissues where their thickness is >0.8 mm caused significant changes in temperature, pH, and ion concentrations. In this study, we developed a multifield and -chamber electrotaxis chip, and various stimulation schemes to determine effective and safe stimulation strategies to guide the migration of human vascular endothelial cells. The electrotaxis chip with a chamber thickness of 1 mm allows 10 voltages applied in one experiment. DC electric fields caused detrimental effects on cells in a 1 mm chamber that mimicking 3D tissue with a decrease in cell migration speed and an increase in necrosis and apoptosis. Using the chip, we were able to select optimal stimulation schemes that were effective in guiding cells with minimal detrimental effects. This experimental system can be used to determine optimal electrical stimulation schemes for cell migration, survival with minimal detrimental effects on cells, which will facilitate to bring electrical stimulation for in vivo use.

Additive Preparation of Conductive Circuit Based on Template Transfer Process Using a Reusable Photoresist

Abstract: To solve the problems of a conventional subtractive process for preparing conductive circuits, numerous alternative additive processes have been investigated, such as screen or inkjet printing, selective electroless plating, laser-induced forward transfer, etc. They all lead to a simpler procedure, less pollution, and finer line width but are still faced with difficulties like low conductivity and thickness, poor adhesion, and high cost. PDMS is a kind of material with low surface energy, leading to low adhesion with adhesive. Under these circumstances, a simple template transfer process for additively preparing conductive circuits is reported. The process to form the template includes the preparation of a photolithographic mask on the carrier copper foil and adsorption of PDMS anti-adhesion coating. Followed by metal deposition through electroplating on the template, the conductive circuits are transferred to the target substrate. Thus, the designed conductive circuits on various substrates including paper and cloth are formed. The template can be used again after being reimmersed into PDMS anti-adhesion coating. The components and the concentration of the coating are carefully discussed, and the mechanism of anti-adhesion is also researched by EIS and XPS. The copper circuits show a line width of 10 μm, a peeling strength of 7.11 N/cm, and a resistivity of 1.93 μΩ·cm, which is similar to that of bulk copper. With low pollution and cost, high versatility, and good electrical and adhesion performance, the template transfer process shows a good application prospect in the large-scale production of flexible electronics like sensors, RFID tags, etc.

Therapeutic Touch: Reactive Clothing for Anxiety

Abstract: The emotional and physical health benefits that come by being touched in safe ways are well established. Therapeutic touch has been used for conditions such as Autism Spectrum Disorder, Attention Deficit Hyperactivity Disorder, Sensory Processing Disorder and Dementia as a calming agent. Smart clothing and textiles have the potential to not only sense, monitor and collect data (inputs) but also to act on the body with embedded actuation capabilities (outputs) such as promoting mechanical, electrical and thermal tactile stimuli. Thus far, the emphasis in the design of wearables, including smart clothing, has been on inputs, with comparatively little research on the responsive output capabilities. This research presents design requirements for development of a user-friendly wearable product for compression therapy and reports development of a reactive undershirt with embedded textile-based pneumatic actuators that deliver tactile stimulation in response to change in emotional state to calm anxiety. The proposed design can offer novel ways of complementing care to empower people with dementia in everyday situations because of its ubiquitous nature and its affordance.

Wearable footwear sensor arrays for detection of cardiac events, body motion, and muscular actions

Abstract: A foot-based wearable system disposed proximate to the dorsalis pedis artery can detect cardiac and muscular activities. Utilizing flexible iontronic sensing (FITS) technology, a sensing array detects both cardiovascular functions, such as heart rate, ECG, and respiration and motion artifact signals with a spatial reference to muscular activities based on the orientation of the array. Individual tendon responses are analyzed and correlated to different pedal gestures, from which multi-channel signals can be used to distinguish different activities. Wearable articles of the invention include a platform to simultaneously analyze both vital signals and body activities from the cardiac waveforms and muscular responses in a natural and unnoticeable fashion. The data-collecting wearable system provides a means to assess personalized health and daily activities on a continuous basis.