An outlook on printed microsupercapacitors: Technology status,remaining challenges,and opportunities

The concept of the Internet of Things is dramatically changing the way society interacts with physical spaces and portable technologies. For the last couple of years, intensive research has been devoted on the design of several flexible and even wearable devices, such as displays and health-care sensors. Further developments on these new technologies are heavily conditioned by the lack of compatible energy storage/conversion units. Contrary to lithium-ion batteries, supercapacitors can be easily miniaturized and integrated on flexible/wearable technologies without losing their electrochemical performance. In this review, some of the most recent developments on the design and printing of light, flexible, and thin microsupercapcitors along with promising and further practical applications are presented.     

印制电路板缺陷图像边缘检测

为了提取含噪声印制电路板(PCB)光板缺陷图像边缘信息,提出了一种基于混合法的图像边缘检测方法.在分析类间最大距离法图像分割基本原理的基础上提出了一种改进的类间最大距离法(IMDBC);设计了结合中值滤波、IMDBC、改进的数学形态学边缘检测算子与LOG算子进行PCB光板缺陷图像边缘检测的混合方法.用CCD及显微镜成像系统获取4幅PCB光板缺陷图像,结果表明:用本文方法提取出的图像边缘信息清晰且较精确,噪声点较少,所得到的4幅图像优质系数是其它6种方法的1.0111~1.3586倍.     

柔性印刷可穿戴电化学传感器

实现对人体的健康监测和慢性病监测是包括材料科学、信息技术、电子技术、分析化学等科学领域在内的世界前沿课题。通过连续获取温度、压力、应力等物理信号来实现对人体活动情况和心率、血压、脑电图、心电图等实时监测的可穿戴设备已实现商业化,但连续监测人体体液、呼出气中的各类化学物质的可穿戴传感器仍面临许多问题,比如传感器的柔韧性、灵敏度、准确性以及与人体皮肤的贴合性等。针对这些问题,本文以柔性印刷技术为出发点,综述了各类柔性基底在电化学传感器/生物传感器领域的应用,同时对可穿戴传感器的发展方向提出了建议。     

正己烷萃取-湿法消解-ICP-MS测定印刷电路板中有机锡

利用正己烷萃取-湿法消解-电感耦合等离子体-质谱(ICP-MS)测定印刷电路板中的有机锡。对ICP-MS测定条件进行了最佳化的选择,选取铟作为内标物,实验表明无机锡不溶于正己烷中。与气相色谱质谱法(GC-MS)对比,本方法可实现有机锡的快速测定。该方法的回收率、精密度和检出限分别为85.6%—96.8%、2.6%—6.5%和0.5mg/kg。     

高效液相色谱法测定印刷线路板热解油中的酚类化合物

建立了反相液相色谱法测定废旧印刷线路板热解油中的酚类化合物的方法,热解油经过滤并溶解在甲醇溶剂中可直接进样进行反相高效液相色谱分析,采用色谱柱为kromasil C18(4.6 mm i.d.×250 mm,5μm);流动相为乙腈/乙酸-乙酸铵缓冲溶液(0.01 mol/L,pH 4.0);柱温25℃;流速为1.0 mL/min,梯度洗脱进行分离,讨论了流动相的组成及其pH值等因素对组分分离产生的影响。实验结果显示,4种酚类化合物线性回归方程的相关系数r为0.9985~0.9996,高、中、低3个添加水平的加标回收率为96.3%~102.6%,相对标准偏差小于6%。     

Flow Injection Analysis of Ascorbyl Glucoside in Cosmetics by a Disposable Printed‐Circuit Board Waste Modified Electrode

Ascorbyl glucoside, i.e., ascorbic acid 2‐glucoside (AA‐2G), is anew type of stable vitamin C derived compound used in many cosmetic skin‐lightening formulations, but rarely studied in the literature. In this study, a screen printed electrode modified with copper‐enriched printed circuit‐board waste (designated as Cu_PCB/SPE) was applied to study the electrochemical characteristics of AA‐2G. Cyclic voltammogram of the Cu_PCB/SPE showed an electrocatalytic oxidative feature at ?0.6 V vs. Ag/AgCl in 0.15 M NaOH solution. Flow injection analysis coupled with the Cu_PCB/SPE was further developed for sensitive AA‐2G determination. The calibration plot was linear in the window of 2.5–160 ppm with slope and regression coefficient of 0.0169 μA/ppm and 0.9971, respectively. The detection limit (S/N = 3) was 0.247 ppm. Real sample analysis was demonstrated for different skin‐lightening cosmetic products with appreciable results.     

Printed electrochemical sensor for ascorbic acid determination

Simple, strip-type sensors based on 7,7,8,8-tetracyanoquinodimethane-modified graphite were prepared using screen printing techniques. The electrochemical strips operated at low potentials [50 mV at pH 7.0 or 100 mV at pH 4.8 vs. Ag/AgCl (printed)] and had a sensitivity of 3.5–7.1 μA 1 mmol^?1L-ascorbic acid. Determination of ascorbic acid concentration was achieved in 30 s and required samples of ca. 30 μl. The current output of the electrodes was found to be relatively insensitive to variations in pH over the range 5.0–8.5. Between 15 and 35 °C, the temperature coefficient was 2.7% °C^?1. The printed electrodes were suitable for single determinations but demonstrated adequate stability for periodic re-use. The ascorbic acid concentration in the juice of fresh fruit was determined using the electrochemical printed electrodes and a commercially available enzymatic test kit. Close agreement was observed between the two methods [r=0.9997 (n=12),slope=0.9798]. The limit of detection using the printed sensor for real samples was calculated as 4mg l^?1(22 μM).     

Prostate Cancer Biomarker Detection with Carbon Nanotubes Modified Screen Printed Electrodes

DNA hypermethylation is an epigenetic alteration and a promising biomarker for early prostate cancer detection. Simple, sensitive, easy to handle and rapid detection methodologies are imperative for point of care diagnostics especially for cancer. Herein, we describe for the first time a regenerable and compatible electrochemical biosensor for detection of Glutathione S‐Transferase P‐1 (GSTP‐1) gene hypermethylation related to prostate cancer via DNA hybridization onto the disposable Carbon and Multi Walled Carbon Nanotubes (MWCNT) Screen Printed Electrodes (SPEs). In the study, capture probes were adsorbed onto the SPEs by simple passive adsorption and then hybridization was achieved by sending the complementary target onto the probe‐modified electrodes. The selectivity of the biosensor was proved by control studies. Differential Pulse Voltammetry (DPV) technique was used to detect hybridization via guanine oxidation signals changes. The total time of the optimized method was nearly 1h, measurements took for less than 1 min, and the biosensor response was stable up to 40 days of storage period at 4 °C. The main advantages of the biosensor are very low detection limit (picomolar range) and capability of reusing the biosensor for at least 3 times after very simple regeneration process that is a unique property to reduce the cost of the assay. In addition, this is the first study that demonstrates the detection of GSTP‐1 hypermethylation electrochemically by using SPEs in order to create point of care diagnostics. The optimum parameters for the biosensor, as well as its future prospects to enhance the performance of DNA biosensors were also presented.     

Electrochemical Oxidation and Sensitive Determination of Pyrogallol at Preanodized Screen‐Printed Carbon Electrodes

In this study, we report a simple, low‐cost and rapid electrochemical sensor based on the anodically pretreated screen‐printed carbon electrodes (SPCE*) for the determination of pyrogallol in pH 7.0 buffer solutions. Cyclic voltammetric studies show that SPCE* lowers overpotentials and improve electrochemical behaviour of pyrogallol, compared to untreated SPCE. All experimental parameters were optimized to improve voltammetric responses; excellent analytical features were achieved by flow‐injection amperometric methods. A linear calibration plot was obtained for 10‐1000 μM pyrogallol with a slope of 0.0562 μA/μM. The detection limit (S/N = 3) was 0.33 μM. Interferences from some inorganic salts and organic compounds were studied. The assay was applied to the determination of pyrogallol in tap water and lake water, respectively.     

Roll-to-roll gravure printed silver patterns to guarantee printability and functionality for mass production

This study introduces mass-producible roll-to-roll (R2R) gravure printed patterns with good printability and functionality. Ag flake materials and polyimide (PI) film substrates were used in this experiment. To confirm mass production potential, a large-scale R2R gravure machine was used, and lengthy printing times were used in the process (6.5 h). It was attempted to print a 30- to 120-μm fine-line pattern (groove type) and a 200- to 1000-μm-wide (dot type) nominal pattern. Various printed width and thickness values were obtained using many measurement sets to confirm the repeatability of each pattern for lengthy process times. We obtained a 45- to 1000-μm pattern width and a 1- to 5-μm thickness. Moreover, resistivity of the printed pattern was also achieved in the range of 5.4–18 μΩ cm. A peel-off test was performed using a standardized method. Finally, this paper presents the achieved optimized process condition and the results of this study.