Study Of Multi-Stimuli Responsive Micromachine

Nature is a source of inspiration for all bionics research.Scientists are enlightened by biological molecular motors(such as myosin,dynein)and biological chemical pump(such as membrane-bound sodium-potassium ion transport pump),and have designed successfully the micromachines which have a variety of structures and driving principles.Micromachine mainly includes the micromotor which can move autonomously in a solution and micropump that is capable of pumping its surrounding solution or small particles,the movement of the micromachine is usually a response to extermal stimulation,but most of the micromachines only respond to the single stimulus,and few studies can realize its on-off-on motion control.If we can prepare micromachine with multi-stimuli responsiveness,we can not only realize precisely control of its movement according to different responses of the micromachine to stimuli,but also the multi-stimuli responsive micromachines may have potential applications in the field of logic gate and directional transportation of materials,etc.In this thesis,we mainly do the research contents of the following two aspects:1.The raspberry-like micromotor with multi-stimuli responsiveness is fabricated by a simple single emulsion solvent evaporation method.It consists of gelatin,catalase and polypyrrole and all three components are known to be nontoxic.and nonharnful biocompatible materials.When placing the raspberry-like micromotor in the aqueous solution containing the H2O2 fuel,owing to the pH-dependent of catalase,the on-off-on motion control of the micromotor can be realized by altematingly adjusting the solution pH to affect the catalytic efficiency of catalase.Under NIR light(808 nm)irradiation;on the one hand,the micromotor can achieve the directional movement due to the photothermal effect of polypyrrole,on the other hand,because the polypyrrole can undergo the reversible deprotonation/reprotonated process under different pH conditions,the light-driven motion of the micromotor can be also tuned on-off-on by altermatingly altering the solution pH to affect the photothermal effect.In addition,the micromotor exhilbits on-off motion behaviors which can be controlled by the application of stimuli such as H2O2 NIR light,NH3,or their combinations.What’s more,the multi-stimuli responsive micromotors show great potential application in the field of logic gate due to the versatility in the motion control.Multiple and reprogrammable OR and INHIBIT logic functions and logic circuit consisting of multiple logic gates(OR,NOT and AND)have been achieved when utilizing H2O2,NIR light,or NH3 as the inputs and the micromotor motion as the output.2.Micromotor and micropump are usually considered as two different devices.The former can be self-propelled,and the latter can drive its surrounding fluid motion,but micronotor and micropump usually do not exist in a system at the same time.We manufactured a micromachine based on polypyrrole which can realize the functions of both micromotor and micropump simultaneously,and it has multiple stimuli responsive property,which not only has a response to near infrared light,but also response to chemical stimuli(such as sodium cholate hydrate).More interestingly,by adjusting the irradiation angle or the concentration of sodium cholate hydrate,we can realize micromotor or micropump behavior simultaneously or separately.The dual-stimuli responsive micromachine which has a combination of micromotor and micropump simultaneously has potential application in biomedical fields,such das the directional transportation and release of drug,etc.