• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Photolithography-free fabrication of photoresist-mold for rapid prototyping of microfluidic PDMS devices

    2022-06-18 03:00:50ShnshnQinGozhiOuBioWngZheyuLiRuiHuYingLiYunhungYng
    Chinese Chemical Letters 2022年2期

    Shnshn Qin, Gozhi Ou, Bio Wng, Zheyu Li,b, Rui Hu,b, Ying Li,b,*,Yunhung Yng,b,*

    a Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071,China

    b University of Chinese Academy of Sciences, Beijing 10049, China

    c School of Physical Education, China University of Geosciences, Wuhan 430074, China

    ABSTRACT Traditional soft lithography based PDMS device fabrication requires complex procedures carried out in a clean room.Herein, we report a photolithography-free method that rapidly produces PDMS devices in 30 min.By using a laser cutter to ablate a tape, a male photoresist mold can be obtained within 5 min by a simple heating-step, which offers significant superiority over currently used photolithographybased method.Since it requires minimal energy to cut the tape, our fabrication strategy shows good resolution (~100 μm) and high throughput.Furthermore, the micro-mold height can be easily controlled by changing the tape types and layers.As a proof-of-concept, we demonstrated that the fabricated PDMS devices are compatible with biochemical reactions such as quenching reaction of KI to fluorescein and cell culture/staining.Collectively, our strategy shows advantages of low input, simple operation procedure and short fabrication time, therefore we believe this photolithography-free method could serve as a promising way for rapid prototyping of PDMS devices and be widely used in general biochemical laboratories.

    Keywords:Microfluidics PDMS Photolithography-free Rapid prototyping Laser cutting Soft lithography

    Microfluidic devices have been widely harnessed in various fields, such as drug screening [1], protein renaturation [2], DNA sequencing [3], cell analysis [4-6], chemical synthesis [7] and others[8].Among various types of microdevices, PDMS-based device is the most popular one utilized in biochemical analysis due to its high precision, low cost, good optical performance and biocompatibility [9].Current PDMS devices are often manufactured based on soft lithography, where a photoresist mold is obtained by photolithography for prototyping [10,11].Since the photoresist mold tightly attaches to a substrate (often a silicon wafer), it allows multiple repeated PDMS pouring and peeling off and contributes to the stability of the following on-chip experiments.Unfortunately,common photolithography requires highly-skilled persons, multiple expensive instruments and complex fabrication procedures performed in a high-maintenance cleanroom (Fig.S1 in Supporting information).These special requirements hinder the accessibility of PDMS devices to the research community, especially for those from general biochemical laboratories without fabrication facilities and experiences [12].

    Fig.1.Laser-cutter based photolithography-free method procedures for prototyping of PDMS devices.(a) Scheme.(b) Experimental processes.

    To simplify the fabrication procedure of microfluidic devices,many methods have been proposed [13].For example, computer numerical control (CNC) micromachining and laser cutter engraving have been widely used to directly fabricate PMMA [14] or even PDMS devices [15], but the generated microchannels often present as a V-shape cross section due to the uneven distribution of laser energy in these relatively stiff materials [16].Laser cutter was also applied to generate microchannels on double-sided adhesive tape that was integrated with a plastic slab and a glass slide to form a microdevice [17].Three-dimensional (3D) printing has also been used to produce devices with scaffolding materials such as acrylonitrile butadiene styrene (ABS) and polyvinyl alcohol (PVA), but the process of dissolving the scaffold could swell the PDMS matrix and the resulted microchannel resolution is relatively low [18].Liquid molding is another rapid prototyping method for PDMS device manufacture [19,20].This strategy is free from expensive instruments for photolithography, but it still needs a premade mask and extra care during PMDS pouring process to avoid water mold disruption [13].Table S1 (Supporting information) shows a brief summarization of currently used methods for rapid microfluidic device fabrication.

    Fig.2.Micropatterns generated based on laser cutting.(a) One- and two-layer tape processed after laser ablation.(b) Micrograph of the PDMS channels after prototyping the photoresist mold.Scale bar, 300 μm.

    Herein, we demonstrate a laser cutter-based fabrication strategy to rapidly generate a tape frame for making positive photoresistbased mold for rapid prototyping of PDMS devices.Since cutting tape requires minimal laser energy, a relatively high-resolution mold (~100 μm) is obtained within 5 minutes by a simple heating step, exempting photolithography steps.As tape thickness and layer number are of flexible selectivity, it is easy to generate microchannels with different heights.This method allows the generation of photoresist molds like traditional photolithography, but eliminates the requirement of clean room facilities and complex procedures (Table S1).The fabricated PDMS devices showed good performance in the proof-of-concept experiments such as chemical reaction monitoring and cell culture.We anticipate this fast, lowcost and flexible fabrication strategy to be widely used in common biochemical laboratories.

    As shown in Fig.1a, the adhesive tape is attached onto a glass slide to carry out the laser cutting.The laser power and scanning speed were optimized to be 1 W and 2.5 cm/s, respectively.After laser ablation (Fig.1a), the tape is transferred to a clean silicon wafer.Then a drop of positive photoresist (SPR 220-7) is applied onto the ablated area of the tape and the extra photoresist is scraped away from the tape with a cover glass.After a simple heating at 65 °C for 2 min, the photoresist-based male mold is obtained after removing the tape.PDMS devices are manufactured by prototyping the mold.The total fabrication time is within 30 min.The experimental fabrication processes are shown in Fig.1b.Since the tape is a thin soft material, it requires minimal energy to cut through and produces little debris and smooth channels.Due to this characteristic of adhesive tape, it is possible to generate relatively higher resolution microstructures when comparing with other hard materials such as PMMA [21,22].As shown in Fig.2,one- or two-layer tape can be processed rapidly and the finally obtained patterns achieved a resolution of ~100 μm.The mold height can be easily controlled by changing tape layers (Fig.2a and Fig.S2 in Supporting information) or using tapes with different thicknesses.This strategy also enables high-throughput fabrication of multiple micropatterns when attaching the tape strips on a large PMMA sheet (Fig.S3 in Supporting information).

    Photoresist-based mold endures high temperature and attaches tightly on the substrate, which allows multiple times of PDMS replication with high fidelity [23].As described above, our strategy only requires two simple steps to get a photoresist-based mold within 5 min.However, current soft lithography needs laborious procedures to fabricate a mold.For example, to obtain a negative photoresist-based (e.g., SU-8) mold, multiple steps are necessary,including spin-coating, pre-bake, UV-exposure (requiring a mask printed in advance), post-bake, developing and hard bake (Fig.S1).These experimental steps, normally performed in a clean room,require the use of many hazardous chemical substances and expensive instruments.It takes about 4 h to finish these procedures.Though typical positive photoresist-based (e.g., SPR220) mold does not necessarily require hard bake, it is essential to perform the other procedures including photolithography.It is known that the UV-exposed area of positive photoresist is dissolved during developing, while the non-exposed area remains on the substrate.In contrast to the traditional way, our strategy directly generates a positive photoresist-based mold by using the laser ablated tape as a constraint frame, which greatly simplifies the fabrication procedure and avoids photolithography and hazardous chemicals.

    Next, we moved to test the performance of the PDMS devices fabricated by using our strategy.As a proof-of-concept experiment for studying chemical reaction, a Y-shape micromixer with a serpentine mixing channel was designed, fabricated and tested(Fig.2a).Quenching reaction of KI to fluorescein is often used to evaluate the mixing performance of a micromixer [24,25].The two solutions were injected into the micromixer from the two inlets.According to Stern-Volmer equation (Eq.1),

    whereI0andIare the fluorescence intensities without and with quenchers respectively,KSVis Stern-Volmer constant(9.608±0.273), [Q] is the concentration of iodide, 70% fluorescence quenching can be achieved if 0.5 mol/L KI is completely mixed with the fluorescein solution.When the flow rate was set as 0.1 mL/h, the fluorescence did not achieve an even distribution at the outlet (Figs.3a and b).When the flow rate was decreased to 0.03 mL/h, the two solutions had sufficient time to diffuse and achieved a complete mixing (the final normalized fluorescence was ~0.3) at the outlet, as shown in Figs.3c and d.

    Fig.3.Results of fluorescence quenching experiment.Fluorescence image under (a) 0.1 and (c) 0.03 mL/h, respectively.Normalized fluorescence intensity at different positions along the microchannel under (b) 0.1 and (d) 0.03 mL/h, respectively.The positions of 0–12 were marked by the purple lines shown in (a) and (c).

    Fig.4.Micrograph showing on-chip cell culture and staining.(a) HeLa cells.(b) U87 cells.

    Furthermore, we tested the biocompatibility of the fabricated PDMS device.Two types of cells (HeLa and U87) with different adhesive behaviors were loaded into the device with a straight channel (Fig.4).HeLa cells are relatively low adhesive, and the cells showed short protrusions after overnight culture.For the U87 (human glioblastoma cell line) cells with a high adhesion ability, long protrusions were monitored.The live/dead staining with calcein and PI demonstrated that both cells showed high viability in the devices, though the image of HeLa cells displayed several red spots that could be cell debris.In a two-day on-chip culture, HeLa cells also demonstrated good status, as shown in the bright-field image in Fig.S4 (Supporting information).These proof-of-concept experiments displayed that the PDMS devices obtained with our strategy have great biocompatibility for cell culture.

    In summary, we proposed a new strategy to fabricate microfluidic PDMS devices within 30 min.Notably, a photoresistbased mold can be obtained in 5 min without photolithography.This method shows a fabrication resolution around 100 μm based on current settings, but better resolution could be achieved by finely tunning the laser power or using an updated laser cutter with higher-resolution lens, which may further promote this technique to be widely used in more refined experiments such as single cell analysis.The surface roughness of the microchannels (e.g., the side wall) could also be improved if the cutting resolution is improved, though current devices already satisfies the requirement of common biochemical reactions (Fig.2b).Two typical biochemical experiments including quenching reaction and cell culture/staining were demonstrated to confirm the device performance.These proof-of-concept studies show that our strategy could serve as an efficient method for rapid prototyping of PDMS devices and holds great potential to be widely used in general biochemical libraries.

    Declaration of competing interest

    The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

    Acknowledgments

    We thank Shunji Li and Dr.Peng Chen for their help in the laser cutter operation.We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.21904139, 22074152, 21735007), Chinese Academy of Sciences(Nos.Y9Y1041001, YJKYYQ20170026).

    Supplementary materials

    Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2021.07.045.

    一区二区三区高清视频在线| 久久午夜亚洲精品久久| 天堂影院成人在线观看| 成人国产综合亚洲| www.色视频.com| 超碰av人人做人人爽久久| 欧美成人一区二区免费高清观看| 观看免费一级毛片| 一级黄色大片毛片| 色吧在线观看| 给我免费播放毛片高清在线观看| 大又大粗又爽又黄少妇毛片口| 国产精品一区二区三区四区免费观看 | 伊人久久精品亚洲午夜| 久久国产乱子免费精品| 一个人观看的视频www高清免费观看| 极品教师在线视频| 亚洲无线观看免费| 少妇被粗大猛烈的视频| 久久午夜福利片| 亚洲不卡免费看| 国产精品乱码一区二三区的特点| 国产高清激情床上av| 极品教师在线免费播放| 国产亚洲欧美98| 国产精品不卡视频一区二区| 在线播放无遮挡| 国产精品电影一区二区三区| 高清日韩中文字幕在线| 久久精品影院6| 床上黄色一级片| 久久香蕉精品热| 一个人看的www免费观看视频| 色哟哟哟哟哟哟| 国产一区二区三区av在线 | 真人做人爱边吃奶动态| 国产免费男女视频| 在线a可以看的网站| 亚洲国产日韩欧美精品在线观看| 国产大屁股一区二区在线视频| 免费一级毛片在线播放高清视频| h日本视频在线播放| 精品福利观看| 2021天堂中文幕一二区在线观| 色综合亚洲欧美另类图片| 观看美女的网站| 97热精品久久久久久| 麻豆精品久久久久久蜜桃| 国产伦在线观看视频一区| 99热这里只有是精品在线观看| 国产又黄又爽又无遮挡在线| 欧美+日韩+精品| 91狼人影院| 国产高清视频在线播放一区| 男女做爰动态图高潮gif福利片| 久久精品国产亚洲av香蕉五月| 男女边吃奶边做爰视频| 日韩欧美精品免费久久| 国产精品久久电影中文字幕| 成人精品一区二区免费| 国产高清不卡午夜福利| 亚洲精品一区av在线观看| 国产三级在线视频| 大型黄色视频在线免费观看| 中文字幕av成人在线电影| 村上凉子中文字幕在线| 久久精品国产亚洲av香蕉五月| 免费不卡的大黄色大毛片视频在线观看 | 中文字幕高清在线视频| 欧美不卡视频在线免费观看| 国产亚洲精品综合一区在线观看| 成人国产综合亚洲| 国产精品久久久久久亚洲av鲁大| 在线观看一区二区三区| 波多野结衣高清作品| 毛片一级片免费看久久久久 | 精品人妻偷拍中文字幕| 我要看日韩黄色一级片| 欧洲精品卡2卡3卡4卡5卡区| 国产精品一区二区性色av| 国产成人福利小说| 老司机午夜福利在线观看视频| 少妇熟女aⅴ在线视频| av中文乱码字幕在线| 露出奶头的视频| 国产成人av教育| 尾随美女入室| 午夜福利18| 亚洲七黄色美女视频| 国产精品久久电影中文字幕| 国产免费一级a男人的天堂| 深夜精品福利| 91麻豆精品激情在线观看国产| h日本视频在线播放| 在线观看舔阴道视频| 少妇的逼水好多| 国产精品1区2区在线观看.| 亚洲av中文av极速乱 | 性插视频无遮挡在线免费观看| 久久九九热精品免费| 91麻豆av在线| 又黄又爽又刺激的免费视频.| 91在线观看av| 一级黄色大片毛片| 人人妻,人人澡人人爽秒播| 国产私拍福利视频在线观看| 床上黄色一级片| 男插女下体视频免费在线播放| 成年免费大片在线观看| 久久久久久久亚洲中文字幕| 婷婷亚洲欧美| 日本免费一区二区三区高清不卡| 少妇丰满av| 一区二区三区四区激情视频 | 男人狂女人下面高潮的视频| 一级黄色大片毛片| 久久久精品欧美日韩精品| 非洲黑人性xxxx精品又粗又长| 内射极品少妇av片p| 男女做爰动态图高潮gif福利片| 国产精华一区二区三区| 在线播放无遮挡| 久久久午夜欧美精品| 在线观看美女被高潮喷水网站| 极品教师在线视频| 麻豆成人av在线观看| 国产欧美日韩精品亚洲av| 欧美xxxx性猛交bbbb| 搞女人的毛片| 精华霜和精华液先用哪个| 久久久久国内视频| 久久久久免费精品人妻一区二区| 草草在线视频免费看| 亚洲最大成人手机在线| 天天一区二区日本电影三级| 久久婷婷人人爽人人干人人爱| 午夜精品在线福利| 搞女人的毛片| 国产主播在线观看一区二区| 精品人妻熟女av久视频| 波野结衣二区三区在线| 我要看日韩黄色一级片| 十八禁国产超污无遮挡网站| 亚洲美女黄片视频| 国内精品宾馆在线| 人妻制服诱惑在线中文字幕| 日日撸夜夜添| 亚洲人成伊人成综合网2020| 国产亚洲精品久久久久久毛片| 成年女人永久免费观看视频| 精品日产1卡2卡| 亚洲国产高清在线一区二区三| 精品久久久久久久久av| 日韩欧美在线二视频| 黄色日韩在线| 亚洲乱码一区二区免费版| 亚洲男人的天堂狠狠| 亚洲欧美日韩高清在线视频| 亚洲成av人片在线播放无| 亚洲av二区三区四区| 欧美日韩黄片免| 午夜福利在线在线| 深夜精品福利| videossex国产| 在线免费观看不下载黄p国产 | 日韩精品青青久久久久久| 好男人在线观看高清免费视频| 精品无人区乱码1区二区| 日日夜夜操网爽| 99视频精品全部免费 在线| 日本色播在线视频| 有码 亚洲区| 亚洲最大成人手机在线| 精品久久久久久成人av| 国产毛片a区久久久久| 九九久久精品国产亚洲av麻豆| 国产亚洲av嫩草精品影院| 国产在线男女| 国产精品久久久久久精品电影| 在线免费十八禁| 欧美人与善性xxx| 国产精品免费一区二区三区在线| 啦啦啦啦在线视频资源| 亚洲成人免费电影在线观看| 亚洲最大成人av| 精品久久久久久成人av| 大型黄色视频在线免费观看| 日韩高清综合在线| 成人高潮视频无遮挡免费网站| 色吧在线观看| 色av中文字幕| 久久精品人妻少妇| 性色avwww在线观看| 亚洲精华国产精华液的使用体验 | 国产真实伦视频高清在线观看 | 22中文网久久字幕| 色精品久久人妻99蜜桃| 熟妇人妻久久中文字幕3abv| 亚洲熟妇熟女久久| 久久久久久久久久久丰满 | 亚洲欧美日韩高清专用| 黄色日韩在线| 日本免费a在线| 国产综合懂色| 男人舔女人下体高潮全视频| 少妇人妻精品综合一区二区 | 级片在线观看| 日韩中字成人| 两人在一起打扑克的视频| 夜夜看夜夜爽夜夜摸| 国产精品女同一区二区软件 | 91久久精品国产一区二区三区| 成熟少妇高潮喷水视频| 日韩欧美国产一区二区入口| 国产欧美日韩一区二区精品| 女同久久另类99精品国产91| 69人妻影院| 国内精品久久久久精免费| 国产真实伦视频高清在线观看 | 国产一区二区三区av在线 | 久久久久国内视频| 黄色一级大片看看| 亚洲av一区综合| 男女那种视频在线观看| 亚洲精品成人久久久久久| 午夜精品在线福利| 精品不卡国产一区二区三区| 69av精品久久久久久| 大又大粗又爽又黄少妇毛片口| 亚洲欧美日韩无卡精品| 亚洲欧美日韩高清专用| 在线天堂最新版资源| 一个人免费在线观看电影| 老女人水多毛片| 搡老岳熟女国产| 真人一进一出gif抽搐免费| 国产伦在线观看视频一区| 五月玫瑰六月丁香| 色尼玛亚洲综合影院| 日本免费一区二区三区高清不卡| 国内精品宾馆在线| 女同久久另类99精品国产91| 少妇猛男粗大的猛烈进出视频 | 免费在线观看日本一区| 色综合亚洲欧美另类图片| 色视频www国产| 亚洲成人免费电影在线观看| 嫩草影院入口| 伊人久久精品亚洲午夜| 亚洲国产欧美人成| 色尼玛亚洲综合影院| 国产精品福利在线免费观看| 熟女人妻精品中文字幕| 两个人的视频大全免费| 日韩高清综合在线| 免费av不卡在线播放| 俄罗斯特黄特色一大片| 欧美潮喷喷水| 免费高清视频大片| 久久久久久久亚洲中文字幕| 亚洲av.av天堂| 中出人妻视频一区二区| 成人av一区二区三区在线看| 久久午夜亚洲精品久久| 一区二区三区激情视频| www.www免费av| 国产午夜精品论理片| 国产精品国产三级国产av玫瑰| 又爽又黄无遮挡网站| 22中文网久久字幕| 亚洲欧美日韩高清专用| 日本-黄色视频高清免费观看| 久久久久久久精品吃奶| 熟妇人妻久久中文字幕3abv| 国产精品女同一区二区软件 | 欧美zozozo另类| 国产欧美日韩精品一区二区| 亚洲精品色激情综合| 欧美高清性xxxxhd video| 色在线成人网| 欧美xxxx性猛交bbbb| 亚洲第一区二区三区不卡| 成人午夜高清在线视频| 国产成人一区二区在线| 国产精品爽爽va在线观看网站| 欧美一级a爱片免费观看看| 最新中文字幕久久久久| 老司机福利观看| 日韩一本色道免费dvd| 久久九九热精品免费| 欧美最新免费一区二区三区| 国产精品久久久久久av不卡| 免费无遮挡裸体视频| 免费看美女性在线毛片视频| 日日摸夜夜添夜夜添av毛片 | 老司机深夜福利视频在线观看| 九色成人免费人妻av| 日本在线视频免费播放| 亚洲精品日韩av片在线观看| 一级av片app| 久久久午夜欧美精品| 岛国在线免费视频观看| 精品久久久久久久久久久久久| 在线播放无遮挡| 日本与韩国留学比较| 亚洲性夜色夜夜综合| 校园春色视频在线观看| 永久网站在线| 极品教师在线免费播放| 欧美高清性xxxxhd video| 欧美日韩黄片免| 国产精品自产拍在线观看55亚洲| 蜜桃久久精品国产亚洲av| 三级国产精品欧美在线观看| 国产精品爽爽va在线观看网站| 99热这里只有精品一区| 99久久久亚洲精品蜜臀av| 男女之事视频高清在线观看| 在线播放国产精品三级| 成人av一区二区三区在线看| 亚洲性夜色夜夜综合| 色尼玛亚洲综合影院| av国产免费在线观看| 99热6这里只有精品| 999久久久精品免费观看国产| 97热精品久久久久久| 99久久九九国产精品国产免费| 国产伦人伦偷精品视频| 国产精品乱码一区二三区的特点| 欧美成人性av电影在线观看| 国产毛片a区久久久久| 一个人免费在线观看电影| 韩国av一区二区三区四区| 久久久久久国产a免费观看| 免费观看精品视频网站| 国产男人的电影天堂91| 欧美潮喷喷水| 色综合站精品国产| 国产精品人妻久久久久久| 天堂√8在线中文| 真实男女啪啪啪动态图| 国产精品国产三级国产av玫瑰| 高清在线国产一区| 国产精品,欧美在线| 亚洲精品乱码久久久v下载方式| 美女大奶头视频| 国产单亲对白刺激| 村上凉子中文字幕在线| 久久99热6这里只有精品| 久久欧美精品欧美久久欧美| 麻豆精品久久久久久蜜桃| 久久久午夜欧美精品| 少妇人妻精品综合一区二区 | 国产在线男女| 国产一区二区三区在线臀色熟女| 国产午夜精品论理片| 俄罗斯特黄特色一大片| 两性午夜刺激爽爽歪歪视频在线观看| 久久6这里有精品| 国产精品乱码一区二三区的特点| 欧美在线一区亚洲| 一级黄色大片毛片| 久久国内精品自在自线图片| 国产女主播在线喷水免费视频网站 | 无人区码免费观看不卡| 日本五十路高清| 三级毛片av免费| 日本黄大片高清| 久久午夜亚洲精品久久| 日本免费一区二区三区高清不卡| x7x7x7水蜜桃| 2021天堂中文幕一二区在线观| 午夜激情欧美在线| 午夜福利18| 国产单亲对白刺激| 一区福利在线观看| 亚洲第一电影网av| 国产精品人妻久久久影院| 亚洲在线观看片| 一进一出好大好爽视频| 亚洲在线自拍视频| 久久精品综合一区二区三区| 久久久久免费精品人妻一区二区| 91在线精品国自产拍蜜月| 又黄又爽又免费观看的视频| 国产精品久久视频播放| 永久网站在线| bbb黄色大片| 波多野结衣高清无吗| 在线看三级毛片| 色在线成人网| 蜜桃久久精品国产亚洲av| 久久久成人免费电影| 亚洲图色成人| 国产91精品成人一区二区三区| av在线老鸭窝| 国产一区二区亚洲精品在线观看| 日韩欧美在线乱码| 我要搜黄色片| 波多野结衣巨乳人妻| 美女黄网站色视频| 午夜精品久久久久久毛片777| 国产在线精品亚洲第一网站| 精品久久久久久久久亚洲 | 91在线观看av| 香蕉av资源在线| 国产精品久久久久久久久免| 成年女人看的毛片在线观看| 久久久精品欧美日韩精品| 国产在线精品亚洲第一网站| 色噜噜av男人的天堂激情| 亚洲欧美激情综合另类| 国产一级毛片七仙女欲春2| 欧美性猛交黑人性爽| 国产aⅴ精品一区二区三区波| 亚洲精品日韩av片在线观看| 国产真实乱freesex| 亚洲人成网站在线播放欧美日韩| 狠狠狠狠99中文字幕| 亚洲成av人片在线播放无| 亚洲国产欧洲综合997久久,| 久久久久久久久久久丰满 | 男女视频在线观看网站免费| 韩国av一区二区三区四区| 国产国拍精品亚洲av在线观看| 内地一区二区视频在线| 91av网一区二区| 午夜激情欧美在线| 一级a爱片免费观看的视频| 日韩欧美在线二视频| 亚洲一级一片aⅴ在线观看| 国产探花在线观看一区二区| 99九九线精品视频在线观看视频| 白带黄色成豆腐渣| 嫁个100分男人电影在线观看| 免费在线观看影片大全网站| 韩国av在线不卡| 午夜影院日韩av| 亚洲男人的天堂狠狠| 丰满人妻一区二区三区视频av| 精品国内亚洲2022精品成人| 亚洲最大成人av| 亚洲欧美日韩东京热| 欧美成人一区二区免费高清观看| 国产高清视频在线播放一区| 欧美中文日本在线观看视频| 听说在线观看完整版免费高清| 精品不卡国产一区二区三区| 欧美日韩中文字幕国产精品一区二区三区| 久久国产精品人妻蜜桃| ponron亚洲| 亚洲欧美日韩卡通动漫| 亚洲欧美日韩高清在线视频| 搡老岳熟女国产| 免费观看的影片在线观看| 中国美白少妇内射xxxbb| 丰满的人妻完整版| 最新在线观看一区二区三区| 日本成人三级电影网站| 天美传媒精品一区二区| 联通29元200g的流量卡| 最新中文字幕久久久久| 国产单亲对白刺激| 日韩人妻高清精品专区| 日本a在线网址| 国产精品野战在线观看| 五月玫瑰六月丁香| 国产在视频线在精品| 国产精品电影一区二区三区| 久久精品久久久久久噜噜老黄 | 国产精品女同一区二区软件 | 婷婷色综合大香蕉| 桃红色精品国产亚洲av| 亚洲成av人片在线播放无| 国产精品一区二区三区四区久久| 亚洲av不卡在线观看| 欧美日本亚洲视频在线播放| 别揉我奶头~嗯~啊~动态视频| 国产一级毛片七仙女欲春2| 禁无遮挡网站| 一进一出抽搐gif免费好疼| 日本欧美国产在线视频| 国产视频一区二区在线看| 日本a在线网址| 日韩在线高清观看一区二区三区 | 51国产日韩欧美| 日本黄大片高清| 免费人成视频x8x8入口观看| 色5月婷婷丁香| 最近视频中文字幕2019在线8| 联通29元200g的流量卡| 国产精品国产三级国产av玫瑰| 直男gayav资源| 在线观看一区二区三区| 内地一区二区视频在线| eeuss影院久久| 国产在线精品亚洲第一网站| 日韩欧美免费精品| 国产高清不卡午夜福利| 中文字幕精品亚洲无线码一区| 日韩精品有码人妻一区| 可以在线观看毛片的网站| 深爱激情五月婷婷| 夜夜看夜夜爽夜夜摸| 麻豆精品久久久久久蜜桃| 精品一区二区免费观看| 国产精品人妻久久久久久| 天天躁日日操中文字幕| 一区二区三区高清视频在线| 亚洲av不卡在线观看| 免费高清视频大片| 看免费成人av毛片| 午夜精品久久久久久毛片777| 精华霜和精华液先用哪个| 亚洲在线观看片| 一个人免费在线观看电影| 久久精品91蜜桃| 国产69精品久久久久777片| 99久久中文字幕三级久久日本| 亚洲精华国产精华液的使用体验 | 两个人视频免费观看高清| 日本黄大片高清| 国产精品伦人一区二区| 精品乱码久久久久久99久播| 日日摸夜夜添夜夜添av毛片 | 人人妻,人人澡人人爽秒播| 直男gayav资源| 露出奶头的视频| 国产高清不卡午夜福利| 日本撒尿小便嘘嘘汇集6| 91麻豆精品激情在线观看国产| 亚洲午夜理论影院| 欧美xxxx黑人xx丫x性爽| 日日啪夜夜撸| 尤物成人国产欧美一区二区三区| 听说在线观看完整版免费高清| 欧美区成人在线视频| xxxwww97欧美| 99热只有精品国产| 国产伦在线观看视频一区| 国产亚洲精品久久久com| 成人三级黄色视频| 国产探花在线观看一区二区| 色播亚洲综合网| 国产精品综合久久久久久久免费| 人妻久久中文字幕网| 色哟哟·www| 亚洲经典国产精华液单| 51国产日韩欧美| 免费av毛片视频| av在线亚洲专区| 亚洲av免费高清在线观看| av国产免费在线观看| 欧美潮喷喷水| 午夜福利在线观看吧| 此物有八面人人有两片| 国内久久婷婷六月综合欲色啪| 成人特级av手机在线观看| 国产老妇女一区| 亚洲欧美激情综合另类| 美女高潮喷水抽搐中文字幕| 成人高潮视频无遮挡免费网站| 简卡轻食公司| 色综合亚洲欧美另类图片| 午夜日韩欧美国产| www.www免费av| av在线观看视频网站免费| 亚洲av成人精品一区久久| 一区二区三区四区激情视频 | 麻豆久久精品国产亚洲av| 99久国产av精品| 久久精品影院6| 国产乱人伦免费视频| 亚洲欧美激情综合另类| 欧美黑人欧美精品刺激| 成人国产综合亚洲| 国内精品久久久久久久电影| 国产精品一及| 少妇熟女aⅴ在线视频| bbb黄色大片| 我的女老师完整版在线观看| 天天一区二区日本电影三级| 日韩 亚洲 欧美在线| 99久久中文字幕三级久久日本| 免费看光身美女| av女优亚洲男人天堂| 少妇丰满av| 在线观看舔阴道视频| 真人一进一出gif抽搐免费| 日本 av在线| 日日摸夜夜添夜夜添av毛片 | 国产 一区精品| 中文字幕久久专区| 亚洲精华国产精华精| 国产午夜精品久久久久久一区二区三区 | 欧美中文日本在线观看视频| 九色成人免费人妻av| 一级黄色大片毛片| 老司机午夜福利在线观看视频| 琪琪午夜伦伦电影理论片6080| 亚洲中文字幕日韩| 中文字幕免费在线视频6| 嫩草影院精品99| 一区二区三区激情视频| 欧美极品一区二区三区四区| 亚洲狠狠婷婷综合久久图片| 身体一侧抽搐| 国内久久婷婷六月综合欲色啪| 观看美女的网站| 成人国产一区最新在线观看| 亚洲av成人精品一区久久| 欧美成人a在线观看| 国产一区二区三区av在线 | 国内精品久久久久精免费| 久久天躁狠狠躁夜夜2o2o|