On-Chip Micro Temperature Controllers Based on Freestanding Thermoelectric Nano Films for Low-Power Electronics

Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics.However,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely challenging.Herein,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2Te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane substrate.Its tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).Moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are observed.Our proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.

Green Fabrication of Freestanding Piezoceramic Films for Energy Harvesting and Virus Detection

Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.

Facile fabrication of ultrathin freestanding nanoporous Cu and Cu-Ag films with high SERS sensitivity by dealloying Mg-Cu(Ag)-Gd metallic glasses

Nanoporous metals prepared by dealloying have attracted increasing attention due to their interesting size-dependent physical,chemical,and biological properties.However,facile fabrication of metallic ultrathin freestanding nanoporous films(UF-NPFs)by dealloying is still challenging.Herein,we report a novel strategy of facile preparation of flexible Cu,Cu_(3)Ag,and CuAg UF-NPFs by dealloying thick Mg-Cu(Ag)-Gd metallic glass ribbons.During dealloying,the local reaction latent heat-induced glass transition of the precursor ribbons leads to the formation of a solid/liquid interface between the initially dealloyed nanoporous layer and the underlying supercooled liquid layer.Due to the bulging effect of in situ generated H2 on the solid/liquid interface,Cu,Cu_(3)Ag,and CuAg UF-NPFs with thicknesses of~200 nm can self-peel off from the outer surface of the dealloying ribbons.Moreover,it was found that the surfaceenhanced Raman scattering(SERS)detection limit of Rhodamine 6G(R6G)on the Cu and CuAg UF-NPF substrates are 10^(-6)M and 10^(-11)M,respectively,which are lower than most of the Cu and Cu-Ag substrates prepared by other methods.This work presents a reliable simple strategy to synthesize a variety of cost effective and flexible metallic UF-NPFs for functional applications.

A generalized synthesis method for freestanding multiferroic twodimensional layered supercell oxide films via a sacrificial buffer layer

Multiferroics are an intriguing family of materials due to the simultaneous presence of two ferroic orderings,namely,ferroelectricity and ferromagnetism.They are scientifically and technologically important and have numerous potential applications,such as four-state logic memories and multiferroic tunneling junctions.However,the growth of epitaxial singlephase multiferroic thin films typically requires single crystalline oxide substrates,which hinders their future integration with Sibased devices.In this study,we report a generalized synthesis method that uses the polydimethylsiloxane(PDMS)-assisted wetetching method with an Sr_(3)Al_(2)O_(6)(SAO)sacrificial layer to transfer freestanding single-phase multiferroic Bi_(2)NiMnO_(6)(BNMO)films from conventional SrTiO_(3)(STO)substrates onto a Si wafer.The structures and properties of the films have been characterized before and after the transfer.These transferred films possess good multiferroic properties on Si wafers,indicating full compatibility with modern Si technology.This method can be generally applicable to other Bi-based multiferroic materials as well.Lastly,the original STO substrates after the transfer process have been recycled for preparing new batches of freestanding BNMO films,indicating a low-cost and sustainable method for manufacturing large-volume freestanding complex oxide thin films.

Freestanding strontium vanadate/carbon nanotube films for long-life aqueous zinc-ion batteries

Aqueous rechargeable zinc-ion battery(ZIB)is considered to be a potential energy storage system for large-scale applications due to its environmental friendliness,high safety,and low cost.However,it remains challenging to develop suitable cathode materials with high specific capacity and long-term cyclic stability.Herein,we have fabricated freestanding Sr0.19V2O51.3H2O/carbon nanotubes(SrVO/CNTs)composite films with different mass ratios by incorporating SrVO into CNTs network.The synthesized SrVO possesses a large interlayer spacing of 1.31 nm,which facilitates Zn(2+)diffusion.Furthermore,the SrVO/CNTs composite film with conductive network structure promotes electron transfer and ensures good contact between SrVO and CNTs during the long-term cycling process.As a result,the battery based on the SrVO/CNTs composite cathode with a mass ratio of 7:3 delivers a specific capacity of 326 mAh·g^(-1)at 0.1 A·g^(-1)and 145 mAh·g^(-1)at 5 A·g^(-1),demonstrating a high capacity and excellent rate capability.Remarkably,the assembled ZIB shows good capacity retention of 91%even after ultra-long cycling for 7500 cycles at a high current rate of 5 Ag^(-1).More importantly,the battery also delivers a high energy density and power density,as 290 Wh·kg^(-1)at 125 W·kg^(-1)(0.1 A·g^(-1)),or 115 Wh·kg^(-1)at 6078 W·kg^(-1)(5 Ag^(-1)).The results demonstrate that the SrVO/CNTs composite is a promising cathode toward large-scale energy storage applications.

Emergent strain engineering of multiferroic BiFeO_(3) thin films

BiFeO_(3),a single-phase multiferroic material,possesses several polymorphs and exhibits a strong sensitivity to strain.Recently,emergent strain engineering in BiFeO_(3) thin films has attracted intense interest,which can overcome the confines of traditional strain engineering introduced through the mismatch between the film and substrate.In this review,we discuss emerging non-traditional strain engineering approaches to create new ground states and manipulate novel functionalities in multiferroic BiFeO_(3) thin films.Through fabricating freestanding thin films,inserting an interface layer or utilizing thermal expansion mismatch,continuously tunable strain can be imposed beyond substrate limitations.Nanostructured evolution and defect introduction are discussed as efficient routes to introduce strain,promising for the development of new nanodevices.Ultrafast optical excitation,growth conditions and chemical doping driven strain are summarized as well.We hope this review will arouse the readers’interest in this fascinating field.

具有增强一致性和透气性的无基底超薄表皮生物电极用于长期生理监测

开发耐用且可靠的生物电极,用以采集高质量的生物电信号,已成为人体生理状态监测和人机交互领域的关键技术.然而,现有的生物电极多基于传统弹性基底,这导致了机械性能不匹配和低渗透性等问题,并且缺乏与生物皮肤类似的多方面属性和必要的协同特性.本研究中,我们报道了一种新型的基于自支撑导电全聚合物薄膜的超薄表皮生物电极(ASU-EBE).该电极将超一致性、优异的拉伸性和透气性集成于一体,展现了约475 S cm^(-1)的高导电性,约48%的出色拉伸性,与生物组织界面的超一致性以及优异的透气性.该电极的电子和机械性能得到提升,这归功于在PEDOT:PSS中引入水溶性聚氧化乙烯,以调节分子间π-π堆积距离,并促进纳米纤维结构的形成.因此,ASU-EBE在与皮肤接触时的阻抗远低于标准凝胶电极,使其成为复杂日常环境下长期医疗监测的理想选择.

Engineering the electronic structure on MXenes via multidimensional component interlayer insertion for enhanced electromagnetic shielding

MXene-based functional electromagnetic interference(EMI)shielding films are highly desirable for mod-ern integrated electronic and telecommunication systems in aerospace,military,artificial intelligence,and smart and wearable electronics field.In this work,3D freestanding Ti_(3)C_(2)T_(x)/CNTs/Ni film assembled by 1D multi-walled carbon nanotubes(MWCNTs)/Ni and 2D Ti_(3)C_(2)T_(x)MXene sheets was synthesized by a facile vacuum filtration process.By electrostatic incorporation,hexagonal nickel plates embed on the CNTs and then the CNTs/Ni insert into the Ti_(3)C_(2)T_(x)layers to form magnetized Ti_(3)C_(2)T_(x)-based functional film with a compact and laminated structure.Due to the outstanding electron migration capacity in the highly conductive Ti_(3)C_(2)T_(x)sheet and multiple internal reflections from porous and segregated structures,the op-timized Ti_(3)C_(2)T_(x)/CNTs/Ni composite films show excellent EMI shielding effectiveness of 67.4 dB with elec-trical conductivity of 744 S cm^(-1).Surprisingly,a magnetization compensation strategy is built to boost the EMI shielding effectiveness with decreased conductivity.Meanwhile,the visual magnetic coupling phenomenon and charge distribution in the heterogeneous interfaces could be observed in the recon-structed electron holography images.Those encouraging results shed light on novel magnetized MXene-based functional films for high-performance EMI shielding.