The Biological Applications Of Silicon Nanowires In Field Effect Transistor Bioprobes And Super-flexibility Radial Junction Optoelectronic Devices

The rapid modernization process has accelerated the pace of human life,and the increasing pressure in work and life has gradually harm people's health.The detection of related biological signals plays an important role in monitoring and preventing diseases.Among them,electrical signals are widely distributed in living organisms,and participate in the regulation of various behaviors of cells.Therefore,from the cellular level,it is of great scientific significance to study the changes of intracellular electrical signals to understand the behavior of cells and organs.However,the traditional probes for cell electrical signal detection are fixed on the surface of the substrate and arranged in an array.The detection relies on the passive attachment of the cells,which prevents the cells from being accurately positioned and hinders the accuracy of their subthreshold events.The measurement inhibited normal migration of the detected cells.The emergence of three-dimensional kinked-type field effect transistor(FET)bioprobes based on silicon nanowire structures opened up new avenues for active,accurate single-cell detection.However,the preparation of bioprobes was complicated,and the low efficiency limited the large-area probes preparation.To this end,this paper uses the IPSLS self-assembled nanowire growth technology pioneered by our research group to prepare the nanowires by morphology programming.Stable growth of the nanowires along the predetermined channel was achieved by regulating the growth parameters.Combined with lithography,sputtering and supercritical drying techniques,the mass production of 14 bioprobes in 1cm2 was achieved.And the transformation and suspension of bioprobes were finally achieved by trying a variety of strategies.On the other hand,implantable electrical stimulation devices are an indispensable medical tool for improving the quality of life and prolonging the life span of patients by stimulating an organ or tissue with an electrical signal to restore normal physiological activity.However,surgical replacement of batteries is unavoidable due to the limited life span of the powered batteries in these devices,which increased pain and morbidity,and even potential risk of death to patients.Since near-infrared light can penetrate human skin,it is believed that the use of optoelectronic devices to convert light transmitted through the skin into electrical energy can achieve battery-free implantable electrical stimulation device.Thus small-sized,wireless optoelectronic devices that can be directly attached to the surface of tissues or organs in vivo become an important development direction for stimulation applications.That is,photovoltaic devices are required to have ultra-flexibility and electrical conductivity.The aluminum foil(AF),which is a conductive and flexible substrate,is an excellent substrate material for ultra-flexible and electrically conductive photovoltaic devices.In this paper,hydrogenated amorphous silicon(a-Si:H)nanowire based thin-film radial junction optoelectronic devices were prepared on the surface of aluminum foil by VLS growth method in PECVD system.And the electrical performances,such as open circuit voltage and short circuit current of the devices were investiged.The voltage-current density curve under light irradiation indicates that the open circuit voltage(Voc)of the photovoltaic device can reached 0.67 V,and its photocurrent density was 12.7mA/cm2,which can meet the electrical performance requirement for various stimulation in vivo.The device was applied to the heart surface of experimental animal(pigs)for direct pacing of heart.Ultra-flexible optoelectronic devices were well conformal to the surface of the heart and can be cut into any small size.The electrons and holes are separated while light illumination,and the conductive aluminum foil is connected to the positively charged p-type SiNWs,which can directly stimulate the surface of the heart and realize the in-situ cardiac pacing stimulation without using the wire to transmit electrical signals.When the stimulation frequency is higher than that governed by the sinus rhythm,a new pacing point can be obtained,which in turn replaces the sinus node for pacing control.The results showed that a pacing frequency of 128 beats/min was obtained after stimulation compared with normal beating of 101 times/min.Here,the preparation,morphology and electrical characterization of bioprobes and nano photoelectric cardiac pacemakers,as well animal experiments were studied,and we provide the main guiding direction for expanding the biological applications of silicon-based nanowire materials.The innovation points of this paper can be summarized as follows:(1)The mass production of silicon nanowire FET bioprobes by IPSLS guided growth method was realized for the first time.The effects of various growth parameters on performance of silicon nanowires were investigated and optimized.The stable transferred method and suspension technology of nanowire bioprobes were developed.This approach overcame the limits of insufficient orientation and batch preparation of the traditional intracellular probe technology,and provided a basis for the detection of single-cell electrophysiological properties actively and accurately.(2)Ultra-flexible conductive amorphous silicon radial junction optoelectronic devices fabricated on aluminum foil surface were obtained.The devices were battery-free,small size,wireless,conductive and can be directly attached to the surface of organs,and could be used to stimulate cardiac for in situ pacing.This study expands the application range of amorphous silicon radial junction photovoltaic devices.