倪凱佳，章海軍，尤清揚(yáng)，張子堯

液體環(huán)境中的光熱微驅(qū)動(dòng)方法與技術(shù)研究

倪凱佳，章海軍*，尤清揚(yáng)，張子堯

浙江大學(xué) 現(xiàn)代光學(xué)儀器國(guó)家重點(diǎn)實(shí)驗(yàn)室，浙江 杭州 310027

提出和發(fā)展了適用于液體(水)環(huán)境的光熱微驅(qū)動(dòng)技術(shù)及光熱微驅(qū)動(dòng)機(jī)構(gòu)(OTMA)。建立了水環(huán)境中OTMA膨脹臂在激光照射下的光熱膨脹模型，基于有限元分析推導(dǎo)出膨脹臂的溫升分布公式，并對(duì)長(zhǎng)度1080mm、寬度90mm的膨脹臂在4 mW激光照射下的溫升分布進(jìn)行了仿真，理論研究表明了液體環(huán)境中光熱微驅(qū)動(dòng)技術(shù)的可行性。設(shè)計(jì)與微加工制作了一種對(duì)稱(chēng)型OTMA，在波長(zhǎng)520 nm、功率可調(diào)的激光照射下，首次實(shí)現(xiàn)了液體環(huán)境中的光熱微驅(qū)動(dòng)，實(shí)驗(yàn)結(jié)果表明膨脹臂的光熱偏轉(zhuǎn)量隨激光功率的增大而增加。進(jìn)一步開(kāi)展了在波長(zhǎng)520 nm、有效功率4 mW、頻率可調(diào)的激光脈沖照射下的光熱微驅(qū)動(dòng)實(shí)驗(yàn)，結(jié)果表明，對(duì)稱(chēng)型OTMA在頻率0.9 Hz～16.4 Hz的激光脈沖照射下具有良好的動(dòng)態(tài)響應(yīng)，驅(qū)動(dòng)量(偏轉(zhuǎn)量)振幅在2.6mm～3.7mm之間變化，隨激光脈沖頻率的增大而減小。理論研究及實(shí)驗(yàn)曲線(xiàn)趨勢(shì)表明，適當(dāng)增大激光功率、提高激光脈沖頻率，在液體環(huán)境中實(shí)現(xiàn)更大偏轉(zhuǎn)量、更高頻率的光熱微驅(qū)動(dòng)是完全可行的。本文研究拓展了液體環(huán)境中的光熱微驅(qū)動(dòng)技術(shù)，為微光機(jī)電系統(tǒng)及微納米技術(shù)領(lǐng)域的應(yīng)用提供了新的方法與途徑。

光熱微驅(qū)動(dòng)技術(shù)；液體環(huán)境；光熱膨脹模型；動(dòng)態(tài)響應(yīng)；偏轉(zhuǎn)量

1 引 言

近年來(lái)，隨著微納米技術(shù)及微機(jī)電系統(tǒng)(micro-nano technology and micro-electromechanical systems，MEMS)與微光機(jī)電系統(tǒng)(micro-opto-elec- tromechanical systems，MOEMS)的快速發(fā)展，微驅(qū)動(dòng)技術(shù)及微驅(qū)動(dòng)器或微驅(qū)動(dòng)機(jī)構(gòu)成為研究熱點(diǎn)?，F(xiàn)有的微驅(qū)動(dòng)技術(shù)包括靜電驅(qū)動(dòng)[1-2]、壓電驅(qū)動(dòng)[3-4]、磁致伸縮驅(qū)動(dòng)[5-6]、形狀記憶合金驅(qū)動(dòng)[7-8]、熱驅(qū)動(dòng)[9-11]與超聲波驅(qū)動(dòng)[12-13]等技術(shù)。

傳統(tǒng)的熱驅(qū)動(dòng)技術(shù)以電熱驅(qū)動(dòng)[14]為主，利用電流流經(jīng)微驅(qū)動(dòng)機(jī)構(gòu)兩個(gè)非對(duì)稱(chēng)的驅(qū)動(dòng)臂，由此產(chǎn)生非對(duì)稱(chēng)的熱變形而實(shí)現(xiàn)微驅(qū)動(dòng)功能。電熱驅(qū)動(dòng)機(jī)構(gòu)具有驅(qū)動(dòng)量大、驅(qū)動(dòng)力強(qiáng)等優(yōu)點(diǎn)[15]。但是，它們需要用導(dǎo)線(xiàn)與外接電源相連，從而限制了其整體機(jī)構(gòu)的微小型化；同時(shí)，電熱驅(qū)動(dòng)機(jī)構(gòu)工作時(shí)需要加熱電流流經(jīng)其內(nèi)部，因此無(wú)法在液體(水)中正常工作，限制了其在液體中的應(yīng)用。

近年來(lái)，我們開(kāi)展了光熱微驅(qū)動(dòng)機(jī)構(gòu)(optothermal microactuator，OTMA)的研究，該類(lèi)驅(qū)動(dòng)機(jī)構(gòu)采用激光作為驅(qū)動(dòng)源直接實(shí)現(xiàn)微驅(qū)動(dòng)，不需要導(dǎo)線(xiàn)與外部電源連接，也無(wú)需加熱電流流經(jīng)驅(qū)動(dòng)機(jī)構(gòu)內(nèi)部?；谶@些特點(diǎn)，OTMA不僅可以應(yīng)用于空氣環(huán)境，而且可以在水或其他液體中正常工作。目前，有關(guān)OTMA及其驅(qū)動(dòng)特性的研究都集中于空氣環(huán)境[16]，而對(duì)OTMA在液體中的驅(qū)動(dòng)及響應(yīng)特性的研究較為欠缺。

為了開(kāi)拓新的光熱微驅(qū)動(dòng)機(jī)構(gòu)的研究應(yīng)用領(lǐng)域，發(fā)展液體環(huán)境中的光熱微驅(qū)動(dòng)技術(shù)，本文開(kāi)展了液體(水)環(huán)境中的OTMA的光熱微驅(qū)動(dòng)理論、方法與實(shí)驗(yàn)研究。建立了水環(huán)境中OTMA的膨脹臂在激光照射下的熱力學(xué)模型，并對(duì)其溫升分布進(jìn)行了仿真，在此基礎(chǔ)上，開(kāi)展了水環(huán)境中OTMA的光熱驅(qū)動(dòng)實(shí)驗(yàn)，證明了這一新技術(shù)的可行性。

2 水環(huán)境中對(duì)稱(chēng)型OTMA的模型及仿真

圖1所示為水環(huán)境中的光熱驅(qū)動(dòng)方法及原理圖，實(shí)驗(yàn)裝置由光熱驅(qū)動(dòng)控制系統(tǒng)和顯微監(jiān)控測(cè)量系統(tǒng)兩大部分組成。前者包括計(jì)算機(jī)及接口、控制電路、半導(dǎo)體激光器、半透半反棱鏡、OTMA和充滿(mǎn)水的玻璃器皿；后者由顯微物鏡、高速CCD(240 f/s)及顯微運(yùn)動(dòng)測(cè)量軟件組成(圖1(a))。計(jì)算機(jī)向控制電路輸出脈沖信號(hào)，通過(guò)改變脈沖信號(hào)的電壓調(diào)節(jié)激光功率，通過(guò)改變控制信號(hào)的脈沖周期調(diào)節(jié)激光脈沖頻率。圖1(b)所示為對(duì)稱(chēng)型OTMA在水環(huán)境中的光熱驅(qū)動(dòng)原理圖，它包括兩條長(zhǎng)度、寬度、厚度的長(zhǎng)薄臂，薄臂左端分別經(jīng)兩條短窄橋與基底相連，薄臂右端直接相連。取其中一條長(zhǎng)薄臂為光熱膨脹臂，并以其左端中點(diǎn)為坐標(biāo)原點(diǎn)建立坐標(biāo)系，設(shè)膨脹臂的長(zhǎng)度方向?yàn)榉较?，寬度方向?yàn)榉较颉＜す馐高^(guò)薄玻璃視窗進(jìn)入水中，照射到膨脹臂上形成一個(gè)直徑2的光斑，設(shè)光斑中心與原點(diǎn)的距離為1；膨脹臂吸收部分激光能量而產(chǎn)生溫升，進(jìn)而在方向伸長(zhǎng)D；基于杠桿放大原理，OTMA在方向偏轉(zhuǎn)D，由此實(shí)現(xiàn)OTMA在水中的光熱微驅(qū)動(dòng)。

需要指出，圖中引入的玻璃視窗，只是為了在實(shí)驗(yàn)過(guò)程中避免氣液界面抖動(dòng)對(duì)激光束造成干擾；在實(shí)際應(yīng)用中，可以將微小型激光器頭部浸入液體中，或用光纖導(dǎo)入激光束直接照射OTMA實(shí)現(xiàn)微驅(qū)動(dòng)。

由于在水中膨脹臂吸收激光能量與散熱的過(guò)程比在空氣中迅速，也就是能夠更快捷地建立熱平衡，因此，雖然本文采用激光脈沖(頻率最高值約為16 Hz)實(shí)現(xiàn)微驅(qū)動(dòng)，在每個(gè)激光脈沖的照射時(shí)間內(nèi)，仍可以基于穩(wěn)態(tài)熱平衡建立膨脹臂的熱力學(xué)模型。如圖2所示，在膨脹臂任意位置處選取一個(gè)長(zhǎng)度為d的微元，并對(duì)該微元在水環(huán)境中的熱平衡及膨脹臂的溫升分布與光熱膨脹進(jìn)行分析。

圖1 水環(huán)境中光熱驅(qū)動(dòng)。(a) 實(shí)驗(yàn)裝置示意圖；(b) 對(duì)稱(chēng)型OTMA的光熱驅(qū)動(dòng)原理圖

圖2 水環(huán)境中膨脹臂的任一微元及其熱流分布示意圖

在d時(shí)間間隔內(nèi)，由于激光照射，該微元獲得熱量a(如果該微元處于照射范圍外，獲得的熱量為0)，通過(guò)傳導(dǎo)從相鄰的前一微元處獲得熱量；同時(shí)，通過(guò)傳導(dǎo)向相鄰的后一微元流失熱量+dx；此外，由于微元上下表面及側(cè)面與水環(huán)境的對(duì)流換熱，損失熱量W、W1、D和D1，表達(dá)式如下：

式中：()為沿方向的激光功率密度分布，為材料的導(dǎo)熱率，()為膨脹臂處的溫度分布，0為環(huán)境溫度(水溫)，D()=()-0表示溫度升高(溫升)值，W為膨脹臂上下表面與水的對(duì)流換熱系數(shù)，D為膨脹臂側(cè)面與水的對(duì)流換熱系數(shù)。設(shè)膨脹臂對(duì)激光能量的吸收系數(shù)為a，沿方向的激光功率密度在激光光斑范圍內(nèi)為常數(shù)0，則整個(gè)膨脹臂區(qū)域內(nèi)激光功率密度分布函數(shù)可表示為

由于與膨脹臂的長(zhǎng)度相比激光光斑尺寸相對(duì)較小，為簡(jiǎn)化起見(jiàn)，可以將激光光斑近似地看作均勻分布，即0(p2)。

在膨脹臂的左右端點(diǎn)=0和=處，單位時(shí)間內(nèi)流向端面的熱量值等于端面換熱失去的熱量值，邊界條件表示為

根據(jù)能量守恒定律，當(dāng)微元處于熱平衡狀態(tài)時(shí)，流入微元的熱量之和等于流出微元的熱量之和，即：

將式(2)中熱量表達(dá)式代入式(4)，并加以簡(jiǎn)化，可得：

結(jié)合邊界條件式(3)，利用特征函數(shù)求解偏微分方程式(5)，可以求解得到水環(huán)境中OTMA的膨脹臂在激光照射下的溫升分布：

根據(jù)上面分段等式，進(jìn)一步對(duì)水環(huán)境中對(duì)稱(chēng)型OTMA膨脹臂在4 mW激光照射下的溫升分布進(jìn)行了MATLAB [MATLAB 9.7.0.1434023(R2019b)，Math Works Inc]仿真。表1給出了由黑色高密度聚丙烯(HDPE)薄片制成的對(duì)稱(chēng)型OTMA的尺寸和熱學(xué)參數(shù)。

仿真得到的膨脹臂的溫升分布如圖3所示，結(jié)果表明，在光斑中心處，膨脹臂的溫升最高，其數(shù)值為53.7 ℃；隨著與光斑中心的距離增大，膨脹臂的溫升隨之減小。由于HDPE材料的熔點(diǎn)在118 ℃以上[17]，因此，當(dāng)水環(huán)境的起始溫度為20 ℃時(shí)，膨脹臂的溫升值在安全范圍內(nèi)，不會(huì)因激光照射而熔化，從而為水環(huán)境中的光熱驅(qū)動(dòng)提供了理論基礎(chǔ)。

表1 對(duì)稱(chēng)型OTMA的尺寸和熱學(xué)參數(shù)

圖3 仿真得到的對(duì)稱(chēng)型OTMA膨脹臂的溫升分布

根據(jù)熱力學(xué)原理，膨脹臂的每一微元將因溫升D()而引起光熱膨脹，從而引起整個(gè)膨脹臂伸長(zhǎng)，伸長(zhǎng)量D可表示為

由圖1可知，當(dāng)膨脹臂在激光照射下沿方向(縱向)伸長(zhǎng)時(shí)，OTMA將產(chǎn)生橫向偏轉(zhuǎn)，基于杠桿原理，該光熱偏轉(zhuǎn)量的理論公式為

其中：為待定的比例系數(shù)，不僅與OTMA的物理及機(jī)械特性有關(guān)，由于OTMA非嚴(yán)格剛性結(jié)構(gòu)，該比例系數(shù)與OTMA運(yùn)動(dòng)相關(guān)。由表1可知，0遠(yuǎn)大于，因此偏轉(zhuǎn)量D比伸長(zhǎng)量D放大了數(shù)十倍，可以通過(guò)光熱驅(qū)動(dòng)實(shí)驗(yàn)進(jìn)行測(cè)量。

3 實(shí)驗(yàn)及結(jié)果

為了實(shí)現(xiàn)水環(huán)境中光熱驅(qū)動(dòng)，并對(duì)OTMA的光熱驅(qū)動(dòng)特性開(kāi)展實(shí)驗(yàn)研究，本文利用準(zhǔn)分子激光微加工系統(tǒng)(Optec Promaster)加工制作了2個(gè)以HDPE為基材、總長(zhǎng)1260 μm的對(duì)稱(chēng)型OTMA(膨脹臂長(zhǎng)度1080 μm、寬度90 μm、厚度20 μm)，一個(gè)用于掃描電子顯微鏡(SEM)成像表征，另一個(gè)用于在水環(huán)境中開(kāi)展光熱驅(qū)動(dòng)實(shí)驗(yàn)。之所以加工2個(gè)相同的OTMA，主要是為了避免SEM掃描成像前濺射鍍膜對(duì)OTMA表面的激光吸收特性造成改變；而在水中進(jìn)行過(guò)光熱驅(qū)動(dòng)實(shí)驗(yàn)的OTMA，又不適合于再進(jìn)行SEM觀測(cè)。圖4所示為第一個(gè)對(duì)稱(chēng)型OTMA的SEM圖像。

上文所述的顯微監(jiān)控測(cè)量系統(tǒng)具有實(shí)時(shí)監(jiān)控和捕獲光熱驅(qū)動(dòng)過(guò)程的功能，采用像素匹配和亞像素?cái)M合算法，測(cè)量在OTMA右端面處選定的特征點(diǎn)的光熱運(yùn)動(dòng)及偏轉(zhuǎn)量(參見(jiàn)圖1(b))。考慮到水對(duì)可見(jiàn)光的吸收率在380 nm～520 nm波段[18]較小，實(shí)驗(yàn)中選用波長(zhǎng)520 nm的激光作為光源。圖5(a)和圖5(b)所示分別為水環(huán)境下對(duì)稱(chēng)型OTMA的原始狀態(tài)和受激光照射時(shí)產(chǎn)生光熱偏轉(zhuǎn)的顯微視頻截圖，可以看到較明顯的橫向偏轉(zhuǎn)，證明了水環(huán)境中光熱驅(qū)動(dòng)方法及技術(shù)的可行性。

圖4 對(duì)稱(chēng)型OTMA的SEM圖像

圖5 水環(huán)境下對(duì)稱(chēng)型OTMA的(a)原始狀態(tài)和(b)受激光照射時(shí)產(chǎn)生光熱偏轉(zhuǎn)的顯微視頻截圖

首先在不同激光功率下(OTMA所處位置處的激光功率)開(kāi)展了水環(huán)境中OTMA的光熱驅(qū)動(dòng)實(shí)驗(yàn)。圖6給出了水環(huán)境中OTMA光熱偏轉(zhuǎn)量隨激光功率變化的關(guān)系曲線(xiàn)，可以看出OTMA膨脹臂偏轉(zhuǎn)量的平均振幅隨激光功率增大而增大，當(dāng)激光功率大于3 mW時(shí)，約成線(xiàn)性關(guān)系，這與伸長(zhǎng)量式(6)、偏轉(zhuǎn)量式(7)的結(jié)論一致；而當(dāng)激光功率小于3 mW時(shí)，考慮是水中的粘滯阻尼的關(guān)系。

基于OTMA光熱偏轉(zhuǎn)與激光功率的關(guān)系，將激光功率調(diào)節(jié)為4 mW時(shí)(預(yù)先在OTMA所處位置測(cè)得的數(shù)值)，在不同激光脈沖頻率下開(kāi)展了水環(huán)境中OTMA的光熱驅(qū)動(dòng)實(shí)驗(yàn)。在實(shí)測(cè)激光脈沖頻率為0.9 Hz、2.9 Hz、4.5 Hz、7.7 Hz、16.4 Hz時(shí)測(cè)得的OTMA偏轉(zhuǎn)運(yùn)動(dòng)曲線(xiàn)如圖7(a)～7(e)所示，圖7(f)給出了OTMA偏轉(zhuǎn)量的平均振幅隨激光脈沖頻率變化的曲線(xiàn)。

實(shí)驗(yàn)結(jié)果表明，當(dāng)激光脈沖頻率為0.9 Hz、2.9 Hz、4.5 Hz、7.7 Hz、16.4 Hz時(shí)，水環(huán)境中OTMA偏轉(zhuǎn)量的平均振幅分別為3.7 μm、3.4 μm、3.2 μm、3.1 μm、2.6 μm。雖然實(shí)驗(yàn)曲線(xiàn)顯示出OTMA振幅隨激光脈沖頻率增大而緩慢減小的趨勢(shì)，但是在頻率16.4 Hz時(shí)OTMA仍有2.8 μm的振幅，說(shuō)明OTMA的響應(yīng)頻率至少在16.4 Hz以上。實(shí)驗(yàn)曲線(xiàn)同時(shí)表明，適當(dāng)增大激光脈沖的頻率和激光功率，可以在水環(huán)境中實(shí)現(xiàn)更高頻率和更大偏轉(zhuǎn)量振幅的光熱驅(qū)動(dòng)。

圖6 水環(huán)境中OTMA光熱偏轉(zhuǎn)量的平均振幅隨激光功率變化的曲線(xiàn)

4 結(jié) 論

本文提出了一種液體(水)環(huán)境中的光熱微驅(qū)動(dòng)方法，發(fā)展了相應(yīng)的光熱微驅(qū)動(dòng)技術(shù)及光熱微驅(qū)動(dòng)機(jī)構(gòu)。針對(duì)對(duì)稱(chēng)型OTMA，研究建立了其在水環(huán)境中的光熱膨脹模型，推導(dǎo)出膨脹臂在激光照射下的溫升分布與光熱膨脹(伸長(zhǎng))量公式，并對(duì)溫升分布進(jìn)行了MATLAB仿真，證明了水環(huán)境中OTMA的光熱膨脹(伸長(zhǎng))及光熱驅(qū)動(dòng)技術(shù)的可行性。

利用準(zhǔn)分子激光微加工系統(tǒng)加工制作了總長(zhǎng)1260 μm，膨脹臂長(zhǎng)度1080 μm、寬度90 μm、厚度20 μm的對(duì)稱(chēng)型OTMA。在波長(zhǎng)520 nm、功率可調(diào)的激光照射下，首次實(shí)現(xiàn)了水環(huán)境中的光熱驅(qū)動(dòng)，實(shí)驗(yàn)結(jié)果表明隨著激光功率的增大，膨脹臂的光熱偏轉(zhuǎn)量也隨之增大，在3 mW以上的激光照射下兩者成線(xiàn)性關(guān)系。進(jìn)一步開(kāi)展了在波長(zhǎng)520 nm、有效功率4 mW、頻率可調(diào)的激光脈沖照射下的水環(huán)境中光熱驅(qū)動(dòng)實(shí)驗(yàn)。實(shí)驗(yàn)結(jié)果表明，OTMA在水環(huán)境中受頻率為0.9 Hz、2.9 Hz、4.5 Hz、7.7 Hz、16.4 Hz的激光脈沖照射時(shí)，可分別獲得平均振幅為3.7 μm、3.4 μm、3.2 μm、3.1 μm、2.6 μm的光熱偏轉(zhuǎn)量，實(shí)現(xiàn)了水環(huán)境中的動(dòng)態(tài)光熱驅(qū)動(dòng)。適當(dāng)增大激光脈沖的頻率和激光功率，可以在水環(huán)境中實(shí)現(xiàn)更高頻率和更大偏轉(zhuǎn)量振幅的光熱驅(qū)動(dòng)。同時(shí)，改變OTMA的結(jié)構(gòu)(如非對(duì)稱(chēng)型OTMA)及采用其他類(lèi)型的液體，也完全可以實(shí)現(xiàn)液體環(huán)境中的光熱驅(qū)動(dòng)。本文的研究工作可為研究開(kāi)發(fā)在水或其他液體中運(yùn)行的特種MEMS/MOEMS設(shè)備，如液體中的光熱微電機(jī)、光熱微泵、光熱微機(jī)器人和其他光熱驅(qū)動(dòng)機(jī)構(gòu)提供技術(shù)基礎(chǔ)。

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Research on optothermal microactuation method and technology in liquid

Ni Kaijia, Zhang Haijun*, You Qingyang, Zhang Ziyao

State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, Zhejiang 310027, China

The symmetric optothermal microactuator operated in water

Overview:With the rapid development of micro-nano technology and micro-electromechanical systems (MEMS) and micro-opto-electromechanical systems (MOEMS), microactuation technology and microactuators or microactuation mechanisms have become research hotspots. Traditional thermal microactuators are mainly based on electrothermal excitation, which obtains thermal deformation by generating ohmic heat of electric current flowing through the asymmetric expansion arms. Such microactuators are capable of gaining larger displacement and generating bigger actuating forces. Contrary to the advantages, the electrothermal microactuators (ETMAs) always require a built-in power source or connecting circuit, resulting in difficulty of miniaturization of the whole device and operating in liquid. In spite of ETMAs, both symmetric and asymmetric OTMAs are available for obtaining microactuation and being applied in water or other liquids without electric circuits and loops. This paper proposes and develops the optothermal microactuation technology and optothermal microactuator (OTMA) suitable for water or other liquids. An optothermal expansion model of the OTMA’s expansion arm in water under laser irradiation is established. The temperature rise distribution formula of the expansion arm is derived by the finite element analysis, and simulation on the expansion arm with a length of 1080 μm and a width of 90 μm under 4 mW laser irradiation is conducted, revealing the feasibility of optothermal microactuation technology in water. The optothermal microactuation experiment of a symmetrical OTMA is carried out in water for the first time under the irradiation of a laser pulse with a wavelength of 520 nm and adjustable power. The results reveal that the amount of optothermal deflection of the expansion arm increases with the increase of the laser power. Another experiment is carried out under the irradiation of a laser pulse with a wavelength of 520 nm, effective power of 4 mW, and an adjustable frequency. The results demonstrate that the symmetric OTMA has a good dynamic response under the laser irradiation. The amplitude of the actuating (deflection) amount varies between 2.6 μm and 3.7 μm when irradiated by the laser pulse with a frequency of 0.9 Hz～16.4 Hz, and it decreases with the increase of the frequency of the laser pulse. The theoretical research and experimental curve trend reveals that it is completely feasible to obtain greater deflection and higher frequency optothermal microactuation in water by appropriately increasing the laser power and laser pulse frequency. This research provides new methods and approaches for the application of micro-opto-electromechanical systems and micro-nano technology.

Ni K J, Zhang H J, You Q Y,Research on optothermal microactuation method and technology in liquid[J]., 2021, 48(11): 210199; DOI:10.12086/oee.2021.210199

Research on optothermal microactuation method and technology in liquid

Ni Kaijia, Zhang Haijun*, You Qingyang, Zhang Ziyao

State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, Zhejiang 310027, China

In this paper, the optothermal microactuation technology and optothermal microactuator (OTMA) suitable for water or other liquids are proposed and developed. The model of optothermal expansion and temperature rise distribution is established, and simulation on a 1080 μm long OTMA is conducted, revealing the feasibility of optothermal microactuation technology in water. The optothermal microactuation experiment of a symmetrical OTMA is carried out in water under the irradiation of a laser with a wavelength of 520 nm and adjustable power, revealing that the optothermal deflection increases with the increase of the laser power. Another experiment is carried out under the irradiation of a laser pulse with a wavelength of 520 nm, effective power of 4 mW, and an adjustable frequency, demonstrating that the symmetric OTMA has a good dynamic response under the laser irradiation. The amplitude of the actuating (deflection) amount varies between 2.6 μm and 3.7 μm when irradiated by the laser pulse with a frequency of 0.9 Hz～16.4 Hz, and it decreases with the increase of the frequency of the laser pulse. The theoretical research and experimental curve trend reveals that it is completely feasible to obtain greater deflection and higher frequency optothermal microactuation in water by appropriately increasing the laser power and laser pulse frequency. This research provides new methods and approaches for the application of micro-opto-electromechanical systems and micro-nano technology.

optothermal microactuation technology; liquid environment; optothermal expansion model; dynamic response; deflection

10.12086/oee.2021.210199

O439；TP211.6

A

National Natural Science Foundation of China (61540019)

* E-mail: zhanghj@zju.edu.cn

倪凱佳，章海軍，尤清揚(yáng)，等. 液體環(huán)境中的光熱微驅(qū)動(dòng)方法與技術(shù)研究[J]. 光電工程，2021，48(11): 210199

Ni K J, Zhang H J, You Q Y,Research on optothermal microactuation method and technology in liquid[J]., 2021, 48(11): 210199

2021-06-09；

2021-09-03基金項(xiàng)目：國(guó)家自然科學(xué)基金資助項(xiàng)目(61540019)

倪凱佳(1996-)，女，碩士研究生，主要從事光熱微驅(qū)動(dòng)技術(shù)的研究。E-mail：si_gnal@163.com

章海軍(1965-)，男，教授，博士生導(dǎo)師，主要從事光學(xué)工程與納米技術(shù)領(lǐng)域的教學(xué)與研究工作。E-mail：zhanghj@zju.edu.cn