Lossless Manipulation Research Articles

"Nanoscale electric vehicle" for the patterning of nanomaterials: Selective electrophoretic deposition of programmable silica composite nanoparticles

Colloidal nanocrystals stand at the forefront of various applications given their unique optoelectronic properties and abundant active sites. However, the surface dynamics of nanocrystals make it difficult to avoid performance sacrifices that result from certain processing methods. Here we introduce a general nanoscale electric vehicle (NEV) platform for efficient and lossless manipulation and processing of functional nanomaterials by selective electrophoretic deposition. Dual-ligand modified system comprising charging ligands and anchoring ligands enables NEV to be universally compatible with fine patterning of various nanomaterials such as quantum dots, perovskites, rare-earth compositions or Janus materials. Without performance impairment from additional modifications, the luminescence performance of the nanocrystals improved significantly with the help of NEV to a level comparable to the commercial standard. Furthermore, we demonstrate the capabilities of our approach for display and anti-counterfeiting encryption applications. Our strategy offers a versatile way of creating high-performance nanomaterial devices in a cost-effective and non-destructive manner.

On-Demand, Contact-Less and Loss-Less Droplet Manipulation via Contact Electrification.

While there are many droplet manipulation techniques, all of them suffer from at least one of the following drawbacks - complex fabrication or complex equipment or liquid loss. In this work, a simple and portable technique is demonstrated that enables on-demand, contact-less and loss-less manipulation of liquid droplets through a combination of contact electrification and slipperiness. In conjunction with numerical simulations, a quantitative analysis is presented to explain the onset of droplet motion. Utilizing the contact electrification technique, contact-less and loss-less manipulation of polar and non-polar liquid droplets on different surface chemistries and geometries is demonstrated. It is envisioned that the technique can pave the way to simple, inexpensive, and portable lab on a chip and point of care devices.

On-demand, remote and lossless manipulation of biofluid droplets

The recent global outbreaks of epidemics and pandemics have shown us that we are severely under-prepared to cope with infectious agents. Exposure to infectious agents present in biofluids (e.g., blood, saliva, urine etc.) poses a severe risk to clinical laboratory personnel and healthcare workers, resulting in hundreds of millions of hospital-acquired and laboratory-acquired infections annually. Novel technologies that can minimize human exposure through remote and automated handling of infectious biofluids will mitigate such risk. In this work, we present biofluid manipulators, which allow on-demand, remote and lossless manipulation of virtually any liquid droplet. Our manipulators are designed by integrating thermo-responsive soft actuators with superomniphobic surfaces. Utilizing our manipulators, we demonstrate on-demand, remote and lossless manipulation of biofluid droplets. We envision that our biofluid manipulators will not only reduce manual operations and minimize exposure to infectious agents, but also pave the way for developing inexpensive, simple and portable robotic systems, which can allow point-of-care operations, particularly in developing nations.

Automated System for Small-Population Single-Particle Processing Enabled by Exclusive Liquid Repellency.

Exclusive liquid repellency (ELR) describes an extreme wettability phenomenon in which a liquid phase droplet is completely repelled from a solid phase when exposed to a secondary immiscible liquid phase. Earlier, we developed a multi-liquid-phase open microfluidic (or underoil) system based on ELR to facilitate rare-cell culture and single-cell processing. The ELR system can allow for the handling of small volumes of liquid droplets with ultra-low sample loss and biofouling, which makes it an attractive platform for biological applications that require lossless manipulation of rare cellular samples (especially for a limited sample size in the range of a few hundred to a few thousand cells). Here, we report an automated platform using ELR microdrops for single-particle (or single-cell) isolation, identification, and retrieval. This was accomplished via the combined use of a robotic liquid handler, an automated microscopic imaging system, and real-time image-processing software for single-particle identification. The automated ELR technique enables rapid, hands-free, and robust isolation of microdrop-encapsulated rare cellular samples.

Reversible lossless manipulation of water droplets with large‐range volume

The lossless manipulation of microdroplets has great promising applications in the fields of such as liquids transportation. In recent years, superhydrophobic surfaces with low adhesion have been utilised as an effective solid surface to realise the lossless transfer of liquids. However, the present methods using superhydrophobic surfaces are hard to realise the reversible lossless manipulation of water droplets with a large-range volume. Here, a special transfer pipette composed of a superhydrophobic hole and an optimised pressure-generation device is developed to realise the lossless manipulation of water droplets. The superhydrophobic surfaces are obtained by electrochemical etching, boiling-water immersion and stearic acid modification, showing an excellent superhydrophobicity with a water contact angle of ~165° and roll-off angle of ~2°. The capture and release of water droplets are realised via controlling the resultant force of the vertical component of capillary force and gravity of droplets. The applied pressure is far less than the threshold pressure which guaranties the lossless property in the manipulation processes. The operable limiting volume of water droplets even reaches to 1404 μL, showing a large-range operable volume. Moreover, the strategy can easily realise the reversible and repeatable manipulation showing potential applications in the biological and microfluidic fields.

Fabrication of Long-Term Underwater Superoleophobic Al Surfaces and Application on Underwater Lossless Manipulation of Non-Polar Organic Liquids

Underwater superoleophobic surfaces have different applications in fields from oil/water separation to underwater lossless manipulation. This kind of surfaces can be easily transformed from superhydrophilic surfaces in air, which means the stability of superhydrophilicity in air determines the stability of underwater superoleophobicity. However, superhydrophilic surfaces fabricated by some existing methods easily become hydrophobic or superhydrophobic in air with time. Here, a facile method combined with electrochemical etching and boiling water immersion is developed to fabricate long-term underwater superoleophobic surfaces. The surface morphologies and chemical compositions are investigated. The results show that the electrochemically etched and boiling-water immersed Al surfaces have excellent long-term superhydrophilicity in air for over 1 year and boehmite plays an important role in maintaining long-term stability of wettability. Based on the fabricated underwater superoleophobic surfaces, a special method and device were developed to realize the underwater lossless manipulation of immiscible organic liquid droplets with a large volume. The capture and release of liquid droplets were realized by controlling the resultant force of the applied driving pressure, gravity and buoyancy. The research has potential application in research-fields such as the transfer of valuable reagents, accurate control of miniature chemical reactions, droplet-based reactors, and eliminates contamination of manipulator components.