Cantilever-free thermal actuation

Brown, Keith A.; Eichelsdoerfer, Daniel J.; Mirkin, Chad A.

doi:10.1116/1.4818259

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…The differences between PPL and DPN largely originate from their material constituents; for example, while feature size in DPN is force independent, the deformable nature of the pens in PPL allows one to rapidly toggle between nanoscale and microscale features by changing the force , and even apply pressure to locally accelerate chemical reactions . PPL also has the advantage that the exceptionally high coefficient of thermal expansion of PDMS allows the use of local heating to physically actuate individual probes in an array. , Another advantage of PPL is that the constituent material of the probes can be readily altered, for example, by adjusting the cross-link density to change the spring constant of individual probes, by including a second, more rigid elastomer at the tip of the pen, or by substituting different polymer materials altogether . Despite extensive research into molecular printing and the recognized importance of moisture in DPN, the role of solvents in PPL has not been studied.…”

Section: Introductionmentioning

confidence: 99%

“…12 PPL also has the advantage that the exceptionally high coefficient of thermal expansion of PDMS allows the use of local heating to physically actuate individual probes in an array. 13,14 Another advantage of PPL is that the constituent material of the probes can be readily altered, for example, by adjusting the cross-link density to change the spring constant of individual probes, 15 by including a second, more rigid elastomer at the tip of the pen, 16 or by substituting different polymer materials altogether. 17 Despite extensive research into molecular printing and the recognized importance of moisture in DPN, the role of solvents in PPL has not been studied.…”

Section: Introductionmentioning

confidence: 99%

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Role of Absorbed Solvent in Polymer Pen Lithography

et al. 2013

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We report on the dynamic role of solvents in molecular printing and show that material transport can be mediated by both environmental solvent (i.e., humidity) and solvent absorbed in the pen. To explore the transport of materials in the absence of environmental solvent, a hydrophobic polymer was patterned using a polydimethylsiloxane (PDMS) pen array that had been soaked in undecane, a nonpolar solvent that readily absorbs into PDMS. We also explored the patterning of the hydrophilic polymer polyethylene glycol (PEG) and found that, even though PDMS only absorbs trace amounts of water, soaking a PDMS pen array in water enables PEG deposition in completely dry environments for over 2 h. We find that the length of time one can pattern in a dry environment is determined by the availability of absorbed solvent, a relationship that we elucidate by comparing the performance of pens with varying ability to absorb water. Furthermore, a calculation accounting for the dynamics of retained water captures these effects completely, allowing for generalization of this result to other solvents and providing a way to tune the desired solvent retention profile. Taken together, this work explores the subtle and dynamic role of solvent on molecular printing and provides an alternative to strict environmental humidity control for reliable molecular printing.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Absorbed Solvent in Polymer Pen Lithography

et al. 2013

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“…This analysis highlighted an important virtue of photoactuators in that they were more efficient than pure thermal actuation. Previously introduced thermal actuators, based upon Joule heating at the glass–PDMS interface, exhibited a maximum a= 100 nm/mW, which indicated that optimized photoactuators are ~2.5 times more effective, in addition to having a far simpler structure [27].…”

Section: Resultsmentioning

confidence: 99%

“…In order to localize the illumination region, glass slides were prepared with aluminum films that included transparent holes, which were made using photolithography, to specify an illumination radius R to be either 1 mm, 500 μm, 250 μm, or 120 μm (Figure 1d). The probe was scanned in tapping mode in a 10×10 nm 2 area, such that the tip was effectively static on the substrate while the feedback tracked the motion of the surface in the vertical direction [19,24,27]. The scan rate of the AFM probe was 0.1 Hz to capture the dynamics of deformation while the AFM executed a single scan line.…”

Section: Methodsmentioning

confidence: 99%

Design of Elastomer-CNT Film Photoactuators for Nanolithography

Huang

Wang

et al. 2019

Polymers

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Polymer pen lithography (PPL) is an approach to multiplexing scanning probe lithography, in which an array of probes on a compliant film-coated rigid substrate are used to write patterns on a surface. Recently, it was shown that these nominally passive pen arrays can be rendered photo-active by making them out of a polydimethylsiloxane (PDMS)–carbon nanotube (CNT) composite. While such photoactuated pens in principle represent a rapid, maskless, and versatile nanomanufacturing strategy, a key challenge that remains is learning how to effectively control the writing of each pen, individually. In this research, we studied the design of PDMS–CNT thin-film photoactuators and experimentally explored the role of illumination radius, film thickness, and CNT concentration. Additionally, we have proposed a model that predicts actuation efficiency, actuation time, and the crosstalk between pens. Based upon these results, we have generated a map of working efficiency to elucidate the ideal choice for specific actuation requirements. This work lays the foundation for studying further photoactuatable composite films as actuators in applications beyond lithography including soft robotics and adaptive optics.

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“…Borrowing techniques from the microfluidics community, , pressurized microchannels can actuate individual pens by moving them in and out of contact with a surface. , However, the scalability of this method is poor as separate pneumatic controls are required for each pen. In contrast, local thermal actuation can be used to reliably actuate pens by taking advantage of the high coefficient of thermal expansion inherent to elastomers (Figure B). , Strikingly, this method can be used to move pens at speeds over 300 μm/s through distances of several micrometers using powers commensurate with those required to operate cantilever-based probes that are thermally actuated, , thereby making it an appealing method for facile large-scale pen actuation. Recently, a method was demonstrated that further improved on the scalability of actuation, wherein the pen array was rendered partially opaque through the inclusion of carbon nanotubes into the elastomeric support and local light absorption was used to actuate pens .…”

Section: Control Over Feature Size With Cf-splmentioning

confidence: 99%

Nanocombinatorics with Cantilever-Free Scanning Probe Arrays

Brown

Hedrick²,

Eichelsdoerfer³

et al. 2018

ACS Nano

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The effectiveness of combinatorial experiments is determined by the rate at which distinct experimental conditions can be prepared and interrogated. This has been particularly limiting at the intersection of nanotechnology and soft materials research, where structures are difficult to reliably prepare and materials are incompatible with conventional lithographic techniques. For example, studying nanoparticle-based heterogeneous catalysis or the interaction between biological cells and abiotic surfaces requires precise tuning of materials composition on the nanometer scale. Scanning probe techniques are poised to be major players in the combinatorial nanoscience arena because they allow one to directly deposit materials at high resolution without any harsh processing steps that limit material compatibility. The chief limitation of scanning probe techniques is throughput, as patterning with single probes is prohibitively slow in the context of large-scale combinatorial experiments. A recent paradigm shift circumvents this problem by fundamentally altering the architecture of scanning probes by replacing the conventionally used cantilever with a soft compliant film on a rigid substrate, a substitution that allows a densely packed array of probes to function in parallel in an inexpensive format. This is a major lithographic advance in terms of scalability, throughput, and versatility that, when combined with the development of approaches to actuate individual probes in cantilever-free arrays, sets the stage for scanning-probe-based tools to address scientific questions through nanocombinatorial studies in biology and materials science. In this review, we outline the development of cantilever-free scanning probe lithography and prospects for nanocombinatorial studies enabled by these tools.

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Cantilever-free thermal actuation

Cited by 6 publications

References 30 publications

Role of Absorbed Solvent in Polymer Pen Lithography

Role of Absorbed Solvent in Polymer Pen Lithography

Design of Elastomer-CNT Film Photoactuators for Nanolithography

Nanocombinatorics with Cantilever-Free Scanning Probe Arrays

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