skip to main content

Title: Fully Additive Electrohydrodynamic Inkjet‐Printed TiO 2 Mid‐Infrared Meta‐Optics

Additive manufacturing at the micron and sub‐micron scale is a rapidly expanding field with electrohydrodynamic inkjet (EHDIJ) printing proving to be a critical fabrication technique that will enable continued advancement. Increasing the range of materials that can be used with EHDIJ printing to create micron and sub‐micron scale features is critical for increasing the variety of devices that can be fabricated with this method. Ceramic, semiconducting, and hybrid organic–inorganic materials are essential for meta‐optics and micro‐electromechanical systems devices, yet these materials are vastly underexplored for applications in EHDIJ printing. A novel printing solution is presented containing a titania alkoxide precursor that is compatible with EHDIJ printing and capable of producing final printed features of 1 µm and below; the highest resolution features ever reported for this family of materials and this method. This solution is used to fabricate the first EHDIJ printed and functioning mid‐infrared meta‐optics lens, capable of focusing 5 µm light.

more » « less
Award ID(s):
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Materials Interfaces
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The advent of 3D printing has facilitated the rapid fabrication of microfluidic devices that are accessible and cost‐effective. However, it remains a challenge to fabricate sophisticated microfluidic devices with integrated structural and functional components due to limited material options of existing printing methods and their stringent requirement on feedstock material properties. Here, a multi‐materials multi‐scale hybrid printing method that enables seamless integration of a broad range of structural and functional materials into complex devices is reported. A fully printed and assembly‐free microfluidic biosensor with embedded fluidic channels and functionalized electrodes at sub‐100 µm spatial resolution for the amperometric sensing of lactate in sweat is demonstrated. The sensors present a sensitive response with a limit of detection of 442 nmand a linear dynamic range of 1–10 mm, which are performance characteristics relevant to physiological levels of lactate in sweat. The versatile hybrid printing method offers a new pathway toward facile fabrication of next‐generation integrated devices for broad applications in point‐of‐care health monitoring and sensing.

    more » « less
  2. Abstract

    As an alternative to traditional photolithography, printing processes are widely explored for the patterning of customizable devices. However, to date, the majority of high‐resolution printing processes for functional nanomaterials are additive in nature. To complement additive printing, there is a need for subtractive processes, where the printed ink results in material removal, rather than addition. In this study, a new subtractive patterning approach that uses electrohydrodynamic‐jet (e‐jet) printing of acid‐based inks to etch nanoscale zinc oxide (ZnO) thin films deposited using atomic layer deposition (ALD) is introduced. By tuning the printing parameters, the depth and linewidth of the subtracted features can be tuned, with a minimum linewidth of 11 µm and a tunable channel depth with ≈5 nm resolution. Furthermore, by tuning the ink composition, the volatility and viscosity of the ink can be adjusted, resulting in variable spreading and dissolution dynamics at the solution/film interface. In the future, acid‐based subtractive patterning using e‐jet printing can be used for rapid prototyping or customizable manufacturing of functional devices on a range of substrates with nanoscale precision.

    more » « less
  3. Abstract

    Printed 2D materials, derived from solution‐processed inks, offer scalable and cost‐effective routes to mechanically flexible optoelectronics. With micrometer‐scale control and broad processing latitude, aerosol‐jet printing (AJP) is of particular interest for all‐printed circuits and systems. Here, AJP is utilized to achieve ultrahigh‐responsivity photodetectors consisting of well‐aligned, percolating networks of semiconducting MoS2nanosheets and graphene electrodes on flexible polyimide substrates. Ultrathin (≈1.2 nm thick) and high‐aspect‐ratio (≈1 μm lateral size) MoS2nanosheets are obtained by electrochemical intercalation followed by megasonic atomization during AJP, which not only aerosolizes the inks but also further exfoliates the nanosheets. The incorporation of the high‐boiling‐point solvent terpineol into the MoS2ink is critical for achieving a highly aligned and flat thin‐film morphology following AJP as confirmed by grazing‐incidence wide‐angle X‐ray scattering and atomic force microscopy. Following AJP, curing is achieved with photonic annealing, which yields quasi‐ohmic contacts and photoactive channels with responsivities exceeding 103 A W−1that outperform previously reported all‐printed visible‐light photodetectors by over three orders of magnitude. Megasonic exfoliation coupled with properly designed AJP ink formulations enables the superlative optoelectronic properties of ultrathin MoS2nanosheets to be preserved and exploited for the scalable additive manufacturing of mechanically flexible optoelectronics.

    more » « less
  4. Along with the increasing interest in MoS 2 as a promising electronic material, there is also an increasing demand for nanofabrication technologies that are compatible with this material and other relevant layered materials. In addition, the development of scalable nanofabrication approaches capable of directly producing MoS 2 device arrays is an imperative task to speed up the design and commercialize various functional MoS 2 -based devices. The desired fabrication methods need to meet two critical requirements. First, they should minimize the involvement of resist-based lithography and plasma etching processes, which introduce unremovable contaminations to MoS 2 structures. Second, they should be able to produce MoS 2 structures with in-plane or out-of-plane edges in a controlled way, which is key to increase the usability of MoS 2 for various device applications. Here, we introduce an inkjet-defined site-selective (IDSS) method that meets these requirements. IDSS includes two main steps: (i) inkjet printing of microscale liquid droplets that define the designated sites for MoS 2 growth, and (ii) site-selective growth of MoS 2 at droplet-defined sites. Moreover, IDSS is capable of generating MoS 2 with different structures. Specifically, an IDSS process using deionized (DI) water droplets mainly produces in-plane MoS 2 features, whereas the processes using graphene ink droplets mainly produce out-of-plane MoS 2 features rich in exposed edges. Using out-of-plane MoS 2 structures, we have demonstrated the fabrication of miniaturized on-chip lithium ion batteries, which exhibit reversible lithiation/delithiation capacity. This IDSS method could be further expanded as a scalable and reliable nanomanufacturing method for generating miniaturized on-chip energy storage devices. 
    more » « less
  5. Abstract

    Despite significant progress in solution‐processing of 2D materials, it remains challenging to reliably print high‐performance semiconducting channels that can be efficiently modulated in a field‐effect transistor (FET). Herein, electrochemically exfoliated MoS2nanosheets are inkjet‐printed into ultrathin semiconducting channels, resulting in high on/off current ratios up to 103. The reported printing strategy is reliable and general for thin film channel fabrication even in the presence of the ubiquitous coffee‐ring effect. Statistical modeling analysis on the printed pattern profiles suggests that a spaced parallel printing approach can overcome the coffee‐ring effect during inkjet printing, resulting in uniform 2D flake percolation networks. The uniformity of the printed features allows the MoS2channel to be hundreds of micrometers long, which easily accommodates the typical inkjet printing resolution of tens of micrometers, thereby enabling fully printed FETs. As a proof of concept, FET water sensors are demonstrated using printed MoS2as the FET channel, and printed graphene as the electrodes and the sensing area. After functionalization of the sensing area, the printed water sensor shows a selective response to Pb2+in water down to 2 ppb. This work paves the way for additive nanomanufacturing of FET‐based sensors and related devices using 2D nanomaterials.

    more » « less