Study On MEMS Experimental Cavity For Biological Ultra-Fast Electron Microscopy

Bio-fast electron microscopy is a new microscopic observation technique developed in recent years.It mainly combines femtosecond laser technology with bio-electron microscopy technology to bioactive samples in picosecond to nanosecond time.The complex transient changes in the non-radiative damage imaging and observation break through the bottleneck of high-dose electron irradiation damage to biologically active samples.In order to solve the observation problem of bioactive solution samples observed by electron microscope,combined with bio-fast electron microscope and MEMS technology,a bio-nano chamber chip stage suitable for biological ultra-fast electron microscopy was designed and fabricated.Processing and modification,so that the chip can maintain the activity of the biological sample,and then use biological ultra-fast electron microscopy to observe the biologically active sample,as follows:(1)A bio-nano chamber chip stage for bio-fast electron microscopy was designed.Based on a<100>type silicon wafer with a 30 nm thick silicon nitride film on both sides,the thickness of the silicon wafer is 200 ?m.The overall structure is formed by the upper,middle and lower three layers through a bond seal to form a bio-nano chamber chip.The upper stage includes an injection window,a sample window and three observation windows.The window size of the observation window is 10x50 ?m,the middle layer is composed of a 300 nm thick indium film,and the lower layer contains three observations.The window,the upper and lower observation windows form a crisscross structure.The upper and lower observation windows of the whole chip are separated from the chamber by a 30 nm thick silicon nitride film.After the injection window and the sample window are sealed,the chamber will be completely isolated from the external environment.(2)Using the MEMS technology,a bio-nano chamber chip stage was prepared.Since the chip unit diameter is less than 3 mm,and the chip fabrication is performed on a 4-inch silicon wafer,and 100 identical chips are simultaneously fabricated on the silicon wafer,the problem of unit dissociation is involved.We compare laser cutting,grinding wheel cutting,and Alkali corrosion dissociation three ways,by studying the characteristics of<100>type silicon wafer in the KOH solution corrosion microstructure,finally developed a solution to dissociate the chip unit by alkali corrosion,successfully yielding the yield of the chip Increased to 100%.(3)By modifying the surface of the nano-chamber chip,it can maintain the activity of the biological sample,and then be used for biological ultra-fast electron microscope observation of the biological sample.The silicon nitride material holds the biologically active sample and cannot maintain the activity of the biological sample.Therefore,we used fibronectin to surface-modify the chip,and through the breast cancer cell culture,it was verified that the modified chip can maintain the activity of the biological sample.We observed dynamic images of active ferritin samples with a diameter of 12-14 nm using a modified bio-nano chamber chip in a bio-rapid electron microscope.