Showing papers by "Tingrui Pan published in 2019"

Flexible and Superwettable Bands as a Platform toward Sweat Sampling and Sensing

Abstract: Wearable biosensors as a user-friendly measurement platform have become a rapidly growing field of interests due to their possibility in integrating traditional medical diagnostics and healthcare management into miniature lab-on-body analytic devices. This paper demonstrates a flexible and skin-mounted band that combines superhydrophobic-superhydrophilic microarrays with nanodendritic colorimetric biosensors toward in situ sweat sampling and analysis. Particularly, on the superwettable bands, the superhydrophobic background could confine microdroplets into superhydrophilic microwells. On-body investigations further reveal that the secreted sweat is repelled by the superhydrophobic silica coating and precisely collected and sampled onto the superhydrophilic micropatterns with negligible lateral spreading, which provides an independent “vessel” toward cellphone-based sweat biodetection (pH, chloride, glucose and calcium). Such wearable, superwettable band-based biosensors with improved interface controllabi...

All-in-One Iontronic Sensing Paper

Abstract: © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1807343 (1 of 11) Paper has been utilized as an ideal platform for chemical, biological, and mechanical sensing for its fibrous structures and properties in addition to its low cost. However, current studies on pressure-sensitive papers have not fully utilized the unique advantages of papers, such as printability, cuttability, and foldability. Moreover, the existing resistive, capacitive, and triboelectric sensing modalities have long-standing challenges in sensitivity, noiseproofing, response time, linearity, etc. Here, a novel flexible iontronic sensing mechanism, referred to as iontronic sensing paper (ISP), is introduced to the classic paper substrates by incorporating both ionic and conductive patterns into an all-in-one flexible sensing platform. The ISP can then be structured into 2D or 3D tactile-sensitive origamis only by the paper-specific manipulations of printing, cutting, folding, and gluing. Notably, the ISP device possesses a device sensitivity of 10 nF kPa−1 cm−2, which is thousands of times higher than that of the commercial counterpart, a resolution of 6.25 Pa, a single-millisecond response time, and a high linearity (R2 > 0.996). Benefiting from the unique properties of the fibrous paper structures and its remarkable performances, the ISP devices hold enormous potential for the emerging human–machine interfaces, including smart packaging, health wearables, and pressure-sensitive paper matrix. disposable, degradable material at a low cost, paper has long been utilized as a flexible platform for chemical and biological sensing. For instance, the pH papers, blood glucose-sensing strips, and early pregnancy detection kits are the most notable ones, along with the recent developments of organic gas sensors, DNA and protein sensors, and heavy ion detection devices.[1–15] Furthermore, benefiting from their fibrous structure, papers can be modified with functional additives, such as carbon-derived materials (e.g., carbon nanotube (CNT) and graphene), conductive polymers, and metallic nanocomposites, leading to new functionalities and sensing modalities.[16–21] Among these emerging functional papers, pressuresensitive papers can be configured with a simple device architecture due to its straightforward sensing principles.[22–25] Although recent studies have successfully exhibited the device flexibility, low-cost manufacturability, and disposability, the additional unique natural advantages of paper have not been fully utilized, such as printability, cuttability, and foldability. The previously reported pressure-sensitive papers, along with the pressure sensors made of them are primarily based on three existing sensing mechanisms, i.e., resistive, capacitive, and triboelectric.[22,26,27] The resistive pressure-sensing papers detect the variations of the electrical resistance induced by the change of the contact area between two resistor structures upon the applied pressure, which can be prepared by dip coating and spray coating of a particular conductive material. Ren’s group has reported a novel graphene paper prepared by immersing tissue papers into a graphene oxide solution, and consecutively, this paper pressure sensing device has exhibited a sensitivity of 17.2 kPa−1 within the range of 2 kPa.[22] Cheng’s group has published a gold nanowire coated paper as a functional sensing material, the prepared pressure sensing device shows a device sensitivity of 1.14 kPa−1 within the range of 5 kPa.[25] However, the nonlinearity between the resistance measurements and the pressure readings can lead to substantial reduction in the device sensitivity as pressure increases. For instance, the sensitivity of the graphene-paper pressure sensor dramatically declines from 17.2 to 0.012 kPa−1 beyond its range limit of 2 kPa, thus restricting its practical utilities and applications.[22] Alternatively, the capacitive pressure-sensitive papers typically utilize parallel electrodes sandwiching a compressible dielectric layer.[28–30] As the loading pressure increases, the distance between two parallel All-in-One Iontronic Sensing Paper

FeetBeat: A Flexible Iontronic Sensing Wearable Detects Pedal Pulses and Muscular Activities

Abstract: Objective : Human feet have long been considered in close association with whole-body health, from which abundant cardiovascular and skeletomuscular information can be extracted. In this study, we aim to develop the world's first foot-based wearable system that can detect both pedal pulses and muscular activities, referred to as FeetBeat. Methods : Utilizing the flexible iontronic sensing technology, we have constructed and characterized a five-unit sensing array for detection of both pedal pulse signals and muscular activities. It is integrated into the tongue of an athletic shoe for real-time signal acquisition. Additionally, the linear array allows alignment-free capture of pulse signals and also provides a spatial reference to muscular activities. Results : An ultrahigh sensitivity of up to 1 nF/mmHg has been achieved for individual units, with a range of 1 to 200 mmHg. The pedal pulse waveforms have been detected to derive vital health signs, such as heart rates (HR) and respiratory rates, of which the pulse-derived HR is compared with the electrocardiogram. Moreover, individual tendon responses have been acquired to analyze different pedal gestures, from which multi-channel signals can be used to distinguish different activities. Conclusion : The FeetBeat device has shown the potential to be the world's first wearable platform to simultaneously analyze both vital signals and body activities from the measurable pedal pulse waveforms and muscular responses in a natural and unobtrusive fashion. The data-collecting wearable system provides a highly valuable means to assess the personalized health as well as daily activities on a continuous basis.

Handwriting Iontronic Pressure Sensing Origami.

Abstract: Origami, the ancient paper folding art, has been investigated from paper electronics to medical equipment and even spaceflight for its amazingly rich scientific foundation of building a complex three-dimensional (3D) structure, saving space, transmitting force, and establishing a load-bearing structure. Introducing origami into flexible pressure sensing will bring a new function to the planar electrical component. In this paper, a flexible iontronic sensing mechanism, handwriting process, and origami were combined into a pressure sensing platform, providing a handwriting iontronic pressure sensing origami with high performance, customized design, and 3D sensing ability. The handwriting process provides a simple, low-cost, efficient, no equipment limitation, and customized manufacturing method in preparing the pressure sensing origami using one commercial paper, while an ionic-electrode interface can be easily constructed by folding. Moreover, the device integrates the advantages of origami of forming a 3D structure, force transmission, and structural support with the pressure sensing function. Notably, the handwriting iontronic pressure sensing origami offers a high device sensitivity of 1.0 nF/(kPa cm2), a detection limitation of 5.12 Pa, a rapid mechanical response time of 6 ms and a reset time of 4 ms, and an ultrahigh repeatability under periodic pressure. Benefiting from the unique properties of origami and the remarkable performances, the proposed handwriting iontronic pressure sensing origami can be highly advantageous for the emerging applications such as STEM education, customized electronic design, human-machine interfaces, etc., where high performance, rapid prototype, and 3D sensing are required.

Microfluidic cap-to-dispense (μCD): a universal microfluidic-robotic interface for automated pipette-free high-precision liquid handling.

Abstract: Microfluidic devices have been increasingly used for low-volume liquid handling operations. However, laboratory automation of such delicate devices has lagged behind due to the lack of world-to-chip (macro-to-micro) interfaces. In this paper, we have presented the first pipette-free robotic-microfluidic interface using a microfluidic-embedded container cap, referred to as a microfluidic cap-to-dispense (μCD), to achieve a seamless integration of liquid handling and robotic automation without any traditional pipetting steps. The μCD liquid handling platform offers a generic and modular way to connect the robotic device to standard liquid containers. It utilizes the high accuracy and high flexibility of the robotic system to recognize, capture and position; and then using microfluidic adaptive printing it can achieve high-precision on-demand volume distribution. With its modular connectivity, nanoliter processability, high adaptability, and multitask capacity, μCD shows great potential as a generic robotic-microfluidic interface for complete pipette-free liquid handling automation.

Combinatorial Peptide Microarray Synthesis Based on Microfluidic Impact Printing.

Abstract: In this Research Article, a novel inkjet printing technique, micro impact printing (MI printing), is applied for the first time to combinatorial peptide microarray synthesis on amine functionalized microdisc arrays through standard Fmoc chemistry. MI printing shows great advantages in combinatorial peptide microarray synthesis compared with other printing techniques, including (1) a disposable cartridge; (2) a small spot size (80 μm) increases array density; (3) minimal loading volume (0.6 μL) and dead volume (<0.1 μL), reduce chemical waste; and (4) multiplexibility of 5 channels/cartridge and capacity of multiple cartridges. Using this synthesis platform, a tetrapeptide library with 625 permutations was constructed and then applied for the screening of ligands targeting α4β1 integrin on Jurkat cells.

Rapid Discovery of Illuminating Peptides for Instant Detection of Opioids in Blood and Body Fluids

Abstract: The United States is currently experiencing an opioid crisis, with more than 47,000 deaths in 2017 due to opioid overdoses. Current approaches for opioid identification and quantification in body fluids include immunoassays and chromatographic methods (e.g., LC-MS, GC-MS), which require expensive instrumentation and extensive sample preparation. Our aim was to develop a portable point-of-care device that can be used for the instant detection of opioids in body fluids. Here, we reported the development of a morphine-sensitive fluorescence-based sensor chip to sensitively detect morphine in the blood using a homogeneous immunoassay without any washing steps. Morphine-sensitive illuminating peptides were identified using a high throughput one-bead one-compound (OBOC) combinatorial peptide library approach. The OBOC libraries contain a large number of random peptides with a molecular rotor dye, malachite green (MG), that are coupled to the amino group on the side chain of lysine at different positions of the peptides. The OBOC libraries were then screened for fluorescent activation under a confocal microscope, using an anti-morphine monoclonal antibody as the screening probe, in the presence and absence of free morphine. Using this novel three-step fluorescent screening assay, we were able to identify the peptide-beads that fluoresce in the presence of an anti-morphine antibody, but lost fluorescence when the free morphine was present. After the positive beads were decoded using automatic Edman microsequencing, the morphine-sensitive illuminating peptides were then synthesized in soluble form, functionalized with an azido group, and immobilized onto microfabricated PEG-array spots on a glass slide. The sensor chip was then evaluated for the detection of morphine in plasma. We demonstrated that this proof-of-concept platform can be used to develop fluorescence-based sensors against morphine. More importantly, this technology can also be applied to the discovery of other novel illuminating peptidic sensors for the detection of illicit drugs and cancer biomarkers in body fluids.

Digital flow rate sensor based on isovolumetric droplet discretization effect by a three-supersurface structure

Abstract: Minute droplets play a growingly important role in the fields of manufacturing and measurement for the ability of being miniscule liquid carries. A digital microfluidic flow rate sensor, which works by counting the number of droplets generated between two electrodes, is designed and fabricated in this article. The droplets with equal volume ranging from nanoliter to microliter are generated by a three-supersurface structure (TSS), and the droplet volume is directly related to the size of gap in the TSS, which means that the resolution of the flow rate sensor can be simply tuned by changing the gap. A theoretical model is presented to reveal the mechanism of the isovolumetric discretization effect, showing that the superhydrophobicity/superhydrophilicity of the TSS’s three surfaces plays the most important role in the isovolumetric droplet discretization. Both numerical simulation and experimental results demonstrate that the droplets can keep uniform size at different flow rates under 200 μL/min, indicating a potential application of the digital flow rate sensor for low rate metering in microfluidic devices.

Digital polymerase chain reaction in an array of microfluidic printed droplets

Abstract: Digital polymerase chain reaction (PCR) is a fast-developed technology, which makes it possible to provide absolute quantitative results. However, this technology has not been widely used in research field or clinical diagnostics. Although digital PCR has been born for two decades, the products on this subject still suffer from either high cost or cumbersome user experience, hence very few labs have the willingness or budget to routinely use such product; On the other hand, the unique sensitivity of dPCR over traditional qPCR shows great potential applications. Here, a cost-effective digital PCR method based on a microfluidic printing system was introduced, trying to overcome those shortcomings. The microfluidic droplet printing technology was utilized in this study to directly generate droplet array containing PCR reaction solution onto the simple glass substrate for the subsequent PCR and imaging, which could be done with any regular flat-panel PCR machine and microscope. With simple analysis, the data generated with this method showed reliable quality, which followed the Poisson distribution trend. Compared with other expensive digital PCR methods, this system is more affordable and simpler to integrate, especially for those biological or medical labs which are in need for the digital PCR options but short in budget. Therefore, this method is believed to have the great potential in the future market application.

Body motion and position sensing, recognition and analytics from an array of wearable pressure sensors

Abstract: Pressure-sensor based arrays are integrated into a control device that detects the position, motion, or movement of a one or more body parts of a user to recognize and translate the motion into a unique user-motion profile. The user motion profile may be independently analyzed or recognized as a discrete motion or gesture and used as input or commands for the control device itself or as a signal or set of signals that yields an output signal to a companion device. The pressure sensors can be attached to any body part of a user, such as the user's wrist or ankle. Motion or position, or changes therein, of the user generates an output signal that may be used to control a companion device. The source of the detectable signal is the pressure-based sensor array that yields a pressure data profile that is translated into an output signal to control the companion device.

On the Sensory Analysis of Matter and Materials

Abstract: If you want to know the weight of a wine glass, you can use a scale. Yet for the wine’s taste, you have to use your tongue, aka the sensory analysis. Still, are there really such two different types of quantities, one that is purely physical and another that is the sensory type? Here, we argue that instinctively designating certain materials attributes as sensory perceptions is unnecessary, considering every scientific concept has (in essence) originated from experience of our sensory organs/brains, i.e., all quantities were initially human perceptions. It seems an attribute or quantity ending up being sensory or not entirely depends on whether initially its physical core in the “perception body” was cleanly extracted, eradicating the physiological and psychological connections.

PIS: Wearable Pedal Iontronic Sensing for Arterial Pulses and Muscular Activities

Abstract: We first introduce a foot-based wearable system named PIS which can both acquire body vital signals and track pedal muscular motions. Such system has been seamlessly integrated into a shoe format by constructing a highly sensitive and flexible pressure sensing array with the novel iontronic sensing principle, reaching a device sensitivity of up to 1 nF/mmHg with a detection range of 1 to 200 mmHg. As a result, we have successfully illustrated that PIS can capture high-definition peripheral arterial pulse waveforms, from which heart rates and respiratory patterns can be extracted within a medical-standard precision. Moreover, the high-spatial resolution of PIS allows alignment-free capture of pulse signals and provides a spatial reference to the pedal structures. It further enables tracking of individual pedal tendon activities, from which the majority of foot gestures can be distinguished.