More Like this

1. AC versus DC field effects on the crystallization behavior of a molecular liquid, vinyl ethylene carbonate (VEC)

   https://doi.org/10.1039/d0cp05290f  

   Duarte, Daniel M.; Richert, Ranko; Adrjanowicz, Karolina (January 2021, Physical Chemistry Chemical Physics)

   null (Ed.)

   Using electric fields to control crystallization processes shows a strong potential for improving pharmaceuticals, but these field effects are not yet fully explored nor understood. This study investigates how the application of alternating high electric fields can influence the crystallization kinetics as well as the final crystal product, with a focus on the possible difference between alternating (ac) and static (dc) type fields applied to vinyl ethylene carbonate (VEC), a molecular system with field-induced polymorphism. Relative to ac fields, static electric fields lead to more severe accumulation of impurity ions near the electrodes, possibly affecting the crystallization behavior. By tuning the amplitude and frequency of the electric field, the crystallization rate can be modified, and the crystallization outcome can be guided to form one or the other polymorph with high purity, analogous to the findings derived from dc field experiments. Additionally, it is found that low-frequency ac fields reduce the induction time, promote nucleation near T g , and affect crystallization rates as in the dc case. Consistency is also observed for the Avrami parameters n derived from ac and dc field experiments. Therefore, it appears safe to conclude that ac fields can replicate the effects seen using dc fields, which is advantageous for samples with mobile charges and the resulting conductivity. 

   more » « less
2. Cell lysis via acoustically oscillating sharp edges

   https://doi.org/10.1039/C9LC00498J  

   Wang, Zeyu; Huang, Po-Hsun; Chen, Chuyi; Bachman, Hunter; Zhao, Shuaiguo; Yang, Shujie; Huang, Tony J. (December 2019, Lab on a Chip)

   In this article, we demonstrate an acoustofluidic device for cell lysis using the acoustic streaming effects induced by acoustically oscillating sharp-edged structures. The acoustic streaming locally generates high shear forces that can mechanically rupture cell membranes. With the acoustic-streaming-derived shear forces, our acoustofluidic device can perform cell lysis in a continuous, reagent-free manner, with a lysis efficiency of more than 90% over a range of sample flow rates. We demonstrate that our acoustofluidic lysis device works well on both adherent and non-adherent cells. We also validate it using clinically relevant samples such as red blood cells infected with malarial parasites. Additionally, the unique capability of our acoustofluidic device was demonstrated by performing downstream protein analysis and gene profiling without additional washing steps post-lysis. Our device is simple to fabricate and operate while consuming a relatively low volume of samples. These advantages and other features including the reagent-free nature and controllable lysis efficiency make our platform valuable for many biological and biomedical applications, particularly for the development of point-of-care platforms. 

   more » « less
3. Single-cell RT-LAMP mRNA detection by integrated droplet sorting and merging

   https://doi.org/10.1039/C9LC00161A  

   Chung, Meng Ting; Kurabayashi, Katsuo; Cai, Dawen (July 2019, Lab on a Chip)

   Recent advances in transcriptomic analysis at single-cell resolution reveal cell-to-cell heterogeneity in a biological sample with unprecedented resolution. Partitioning single cells in individual micro-droplets and harvesting each cell's mRNA molecules for next-generation sequencing has proven to be an effective method for profiling transcriptomes from a large number of cells at high throughput. However, the assays to recover the full transcriptomes are time-consuming in sample preparation and require expensive reagents and sequencing cost. Many biomedical applications, such as pathogen detection, prefer highly sensitive, reliable and low-cost detection of selected genes. Here, we present a droplet-based microfluidic platform that permits seamless on-chip droplet sorting and merging, which enables completing multi-step reaction assays within a short time. By sequentially adding lysis buffers and reactant mixtures to micro-droplet reactors, we developed a novel workflow of single-cell reverse transcription loop-mediated-isothermal amplification (scRT-LAMP) to quantify specific mRNA expression levels in different cell types within one hour. Including single cell encapsulation, sorting, lysing, reactant addition, and quantitative mRNA detection, the fully on-chip workflow provides a rapid, robust, and high-throughput experimental approach for a wide variety of biomedical studies. 

   more » « less
4. High surface area reverse electrowetting energy harvesting with power conditioning circuitry for self-powered motion sensors

   https://doi.org/10.1117/12.2587541  

   Adhikari, Pashupati R.; Biswas, Dipon K.; Tasneem, Nishat T.; Reid, Russell C.; Mahbub, Ifana (April 2021, SPIE Defense + Commercial Sensing)

   Dutta, Achyut K.; Balaya, Palani; Xu, Sheng (Ed.)

   Monitoring human health in real-time using wearable and implantable electronics (WIE) has become one of the most promising and rapidly growing technologies in the healthcare industry. In general, these electronics are powered by batteries that require periodic replacement and maintenance over their lifetime. To prolong the operation of these electronics, they should have zero post-installation maintenance. On this front, various energy harvesting technologies to generate electrical energy from ambient energy sources have been researched. Many energy harvesters currently available are limited by their power output and energy densities. With the miniaturization of wearable and implantable electronics, the size of the harvesters must be miniaturized accordingly in order to increase the energy density of the harvesters. Additionally, many of the energy harvesters also suffer from limited operational parameters such as resonance frequency and variable input signals. In this work, low frequency motion energy harvesting based on reverse electrowetting-ondielectric (REWOD) is examined using perforated high surface area electrodes with 38 µm pore diameters. Total available surface area per planar area was 8.36 cm2 showing a significant surface area enhancement from planar to porous electrodes and proportional increase in AC voltage density from our previous work. In REWOD energy harvesting, high surface area electrodes significantly increase the capacitance and hence the power density. An AC peak-to-peak voltage generation from the electrode in the range from 1.57-3.32 V for the given frequency range of 1-5 Hz with 0.5 Hz step is demonstrated. In addition, the unconditioned power generated from the harvester is converted to a DC power using a commercial off-theshelf Schottky diode-based voltage multiplier and low dropout regulator (LDO) such that the sensors that use this technology could be fully self-powered. The produced charge is then converted to a proportional voltage by using a commercial charge amplifier to record the features of the motion activities. A transceiver radio is also used to transmit the digitized data from the amplifier and the built-in analog-to-digital converter (ADC) in the micro-controller. This paper proposes the energy harvester acting as a self-powered motion sensor for different physical activities for wearable and wireless healthcare devices. 

   more » « less
5. Establishing Digital Recognition and Identification of Microscopic Objects for Implementation of Artificial Intelligence (AI) Guided Microassembly

   Zhou, Tuo; Yu, Shih-Yuan; Michaels, Matthew; Du, Fangzhou; Kulinsky, Lawrence; Al Faruque, Mohammad Abdullah (October 2021, Proceedings of World Congress on Micro and Nano Manufacturing 2021)

   As miniaturization of electrical and mechanical components used in modern technology progresses, there is an increasing need for high-throughput and low-cost micro-scale assembly techniques. Many current micro-assembly methods are serial in nature, resulting in unfeasibly low throughput. Additionally, the need for increasingly smaller tools to pick and place individual microparts makes these methods cost prohibitive. Alternatively, parallel self-assembly or directed-assembly techniques can be employed by utilizing forces dominant at the micro and nano scales such as electro-kinetic, thermal, and capillary forces. However, these forces are governed by complex equations and often act on microparts simultaneously and competitively, making modeling and simulation difficult. The research in this paper presents a novel phenomenological approach to directed micro-assembly through the use of artificial intelligence to correlate micro-particle movement via dielectrophoretic and electro-osmotic forces in response to varying frequency of an applied non-uniform electric field. This research serves as a proof of concept of the application of artificial intelligence to create high yield low-cost micro-assembly techniques, which will prove useful in a variety of fields including micro-electrical-mechanical systems (MEMS), biotechnology, and tissue engineering. 

   more » « less