Journal: Nanophotonics

Article Title: Direct electron beam patterning of electro-optically active PEDOT:PSS

doi: 10.1515/nanoph-2023-0640

Figure Lengend Snippet: High resolution, direct patterning of PEDOT:PSS via electron beam induced solubility modulation. (a) Schematic illustration of the fabrication workflow for direct electron beam lithography (EBL). The metallic polymer PEDOT:PSS is spin-coated onto a 20 nm indium-tin-oxide (ITO) coated glass substrate. No additional heat- or post-treatment is required. The metallic polymer is directly patterned via electron beam lithography. After the sample has been developed for 90 s in H 2 O to remove the unexposed material, an electrically switchable metallic polymer structure is obtained. (b) Schematic of the electrochemical setup and the switching behavior. Dark blue indicates the insulating state. (c) Switching of visible electrochromism between the on- and off-state is demonstrated with optical micrographs of a patterned Stanford logo measured in transmission (upper) and a patterned Stuttgart logo measured in reflection (lower) upon switching of the applied potential between 0.5 V and −0.5 V in a three electrode electro-chemical set-up in the aqueous electrolyte, phosphate buffered saline (PBS). The voltage is applied to the working electrode (WE), an ITO coated glass substrate on which the structures are fabricated, relative to an Ag/AgCl reference electrode (RE), with a Pt wire serving as a counter-electrode (CE). The voltage change leads to a color variation visible in the two logos. (d) Scanning electron microscope (SEM) images to demonstrate the achievable resolution with metallic polymer gratings produced via our direct fabrication scheme. The periodicity for all gratings is 3 µm while the width w of the wires is reduced from 1 µm to 250 nm. The film thickness of the PEDOT:PSS layer is 90 nm for all measurements.

Article Snippet: All processes were developed using commercial PEDOT:PSS (Clevios PH1000, 1.3 wt percent) purchased from Ossila.

Techniques: Solubility, Polymer, Transmission Assay, Saline, Microscopy, Produced

Journal: Nanophotonics

Article Title: Direct electron beam patterning of electro-optically active PEDOT:PSS

doi: 10.1515/nanoph-2023-0640

Figure Lengend Snippet: Comparison of conductivity and electrochemical properties of pristine and chemically crosslinked (red) with EBL exposed (blue) PEDOT:PSS. (a) Conductivity of pristine and EBL exposed PEDOT:PSS samples as determined by a 4-point probe measurement without any additives (left) and with inclusion of the additive, ethylene glycol, common used to enhance conductivity (right). (b and c) Electrochemical properties of EBL exposed PEDOT:PSS in phosphate buffered saline solution compared to PEDOT:PSS chemically crosslinked with the standard chemical cross-linker, (3-glycidyloxypropyl)trimethoxysilane, studied through (b) cyclic voltammetry and (c) electrochemical impedance spectroscopy, represented through a Bode plot. Measurements were conducted in a custom-built electrochemical cell. Gold (70 nm, 5 nm Ti adhesion layer) coated Si was used as a substrate and working electrode, an Ag/AgCl pellet electrode was used as a reference electrode and a platinum wire was used as a counter electrode.

Article Snippet: All processes were developed using commercial PEDOT:PSS (Clevios PH1000, 1.3 wt percent) purchased from Ossila.

Techniques: Comparison, Saline, Impedance Spectroscopy

Journal: Nanophotonics

Article Title: Direct electron beam patterning of electro-optically active PEDOT:PSS

doi: 10.1515/nanoph-2023-0640

Figure Lengend Snippet: Comparison of optical properties of pristine (red) and EBL exposed (blue) PEDOT:PSS. (a and b) Transmission spectra measured with UV–vis spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. The pristine and the EBL exposed film is about 90 nm in thickness. In (a) the transmittance was measured between 380 nm and 800 nm. The reference signal was measured through the bare glass substrate. In (b) the transmittance was measured between 1 µm and 10 µm. For this measurement the PEDOT:PSS film was spin-coated on a double-side polished silicon wafer and the reference signal was measured through the bare silicon substrate. (c) Resulting optical constants derived from variable angle spectroscopic ellipsometry measurements. Here, the real part ε 1 (solid line) and imaginary part ε 2 (dotted line) of the dielectric function ε = ε 1 + i ε 2 are presented for the metallic polymer PEDOT:PSS in the in-plane sample axis in the pristine and EBL exposed state. In the ellipsometry measurements, four angles of incidence were used for the pristine material and two angles were used for the EBL exposed material. To obtain a good agreement between the measurement and the model, a combination of spectroscopic ellipsometry and transmission data was used. Both models were generated between 400 nm and 1650 nm and are based on an anisotropic generalized oscillator approach. For the pristine PEDOT:PSS, a mean square error (MSE) of 2.2, and for the EBL exposed material an MSE value of 8.8 was obtained. For the pristine state, a metallic polymer with ε 1 < 0 is obtained for λ > 1.6 µm. For the EBL-exposed material, metallic properties with ε 1 < 0 are obtained for λ > 1.35 µm.

Article Snippet: All processes were developed using commercial PEDOT:PSS (Clevios PH1000, 1.3 wt percent) purchased from Ossila.

Techniques: Comparison, Transmission Assay, UV-Vis Spectroscopy, Fourier Transform Infrared Spectroscopy, Spectroscopy, Derivative Assay, Polymer, Generated

Journal: Nanophotonics

Article Title: Direct electron beam patterning of electro-optically active PEDOT:PSS

doi: 10.1515/nanoph-2023-0640

Figure Lengend Snippet: Conducting polymer PEDOT:PSS diffraction grating and diffraction angle variation by changing the periodicity. Presentation of the fabricated diffraction gratings via (a) a microscope image and (b) an SEM image of a section of the structure. The length and width of the diffraction grating arrays are 500 µm. In (b) the periodicity is 6 µm and the width of the metallic polymer wires is 2 µm. (c) Variation of the diffraction angle between 30° and 12.4° by changing the periodicity and width of the diffraction grating while keeping the aspect ratio constant at 1/3. The periodicity is increased from 3 µm to 7 µm and the width of the wires is adjusted accordingly. The zeroth- and first-order are clearly visible in the IR camera images and by increasing the periodicity the diffraction angle is decreased. To prevent saturation of the IR camera the transmitted beam is attenuated. The measurement is performed at a wavelength of 1.5 µm.

Article Snippet: All processes were developed using commercial PEDOT:PSS (Clevios PH1000, 1.3 wt percent) purchased from Ossila.

Techniques: Polymer, Microscopy

Journal: Nature Communications

Article Title: Sensing and memorising liquids with polarity-interactive ferroelectric sound

doi: 10.1038/s41467-019-11478-1

Figure Lengend Snippet: Device architecture and working principle. a Conceptual illustration of liquid-interactive ferroelectric sound (LIFS) in our tube-type alternating current (AC) device containing a ferroelectric PVDF-TrFE tube with two pairs of in-plane electrodes on the surface of the tube. LIFSs with different sound pressure levels (SPLs) are developed using liquids with different polarities. A schematic of a flexible planar-type LIFS AC device is also shown with three layers of two in-plane PEDOT:PSS electrodes. b Photographs of planar-type LIFS AC devices with deionised water and PEDOT:PSS solution in water placed on the devices. c AC voltages measured between one of the bottom PEDOT:PSS electrodes and various liquids deposited on an LIFS AC device as a function of frequency at the voltage of 100 V. Finite element method (FEM) results of the LIFS AC device under a voltage bias between two in-plane electrodes showing both the direction and magnitude of the generated electric field without ( d ) and with ( e ) a top conductive layer on PVDF-TrFE. f Schematic illustration of non-volatile writing, reading, and erasing of the information of a liquid with an LIFS AC device in terms of liquid-polarity-dependent ferroelectric polarisation, which can be in turn converted into non-volatile SPL

Article Snippet: PEDOT:PSS (Clevios PH 1000), Zonyl surfactant (FS-300 fluoro-surfactant), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich.

Techniques: Generated

Journal: Nature Communications

Article Title: Sensing and memorising liquids with polarity-interactive ferroelectric sound

doi: 10.1038/s41467-019-11478-1

Figure Lengend Snippet: Non-volatile liquid-interactive sensing memory. a Schematics of the device structure for liquid sensing memory. An liquid-interactive ferroelectric sound (LIFS) arising from remnant polarisation of a liquid ( P r-L ) developed in the write step is read in terms of SPL with a reference PEDOT:PSS solution in water. b Sound pressure level (SPL) values of LIFSs written with five liquids with different polarities and subsequently read with the reference PEDOT:PSS solutions after removal of the liquids. c Write-erase cycle endurance of an LIFS alternating current (AC) device with deionised water. SPL value arising from the LIFS of deionised water was substantially reduced after erasing the written remnant polarisation. Re-writing of the device with deionised water resulted in an SPL value almost identical to that in the first writing step. Ten write-erase cycles were reliably achieved with significant variation of SPL. d Variation of SPL values of an LIFS AC device upon multiple cycles of consecutive write with deionised water, erase, re-write with ethanol, and erase. Two characteristic SPL values of 65 and 55 dB written with deionised water and ethanol, respectively, are apparent after the multiple cycles. e Time-dependent retention of SPL value arising from an LIFS of deionised water. Direct current (DC) voltages of 2 and −1 kV were used for writing and erasing for all the liquids, respectively. The reading was obtained for all the liquids at an AC frequency and voltage of 20 kHz and 100 V, respectively. The electrode spacing of all samples is 12 mm

Article Snippet: PEDOT:PSS (Clevios PH 1000), Zonyl surfactant (FS-300 fluoro-surfactant), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich.

Techniques:

Journal: Nature Communications

Article Title: Sensing and memorising liquids with polarity-interactive ferroelectric sound

doi: 10.1038/s41467-019-11478-1

Figure Lengend Snippet: Position detection of a liquid droplet by liquid-interactive ferroelectric sound. a Schematics of four sets of 3 × 3 liquid position detection pads for single and multi-droplet position detection. A schematic and a photograph of a single liquid-interactive ferroelectric sound (LIFS) alternating current (AC) device pixel with PDMS space. b Table showing the position marking process. Each 3 × 3 array pad was programmed with nine different direct current (DC) voltages ranging from 1.0 kV to 1.40 kV to develop nine different marking zones with different remnant polarisation values. Zones 1, 2, 3, and 4 were programmed with Ethanol, DI water, 5 wt% LiCl (a.q.) and PEDOT:PSS solution, respectively. The four different AC frequencies of 14, 16, 18, and 20 kHz were applied to zones 1, 2, 3, and 4, respectively, during the reading process. c Sound pressure level (SPL) spectra of the nine positions of each zone. Owing to the different reading frequency values of 14, 16, 18, and 20 kHz, nine positions of each 3 × 3 array pad were clearly resolved in the SPL. Nine different SPL values for each liquid were obtained, depending on the position, allowing for sound-based position detection of a liquid. d A photograph of the position detection pad with Ethanol (1–2), DI water (2–4), 5 wt% LiCl (a.q.) (3–6), and PEDOT:PSS solution droplets (4–8). e SPL spectra arising from the four droplets on the position detection pad. All SPL values were obtained at a voltage of 100 V

Article Snippet: PEDOT:PSS (Clevios PH 1000), Zonyl surfactant (FS-300 fluoro-surfactant), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich.

Techniques:

Journal: Nature Communications

Article Title: Sensing and memorising liquids with polarity-interactive ferroelectric sound

doi: 10.1038/s41467-019-11478-1

Figure Lengend Snippet: Dynamic monitoring of liquids by liquid-interactive ferroelectric sound. a A photograph of an liquid-interactive ferroelectric sound (LIFS) alternative current (AC) device with three in-plane PEDOT:PSS electrodes for monitoring the velocity of a liquid in microfluidic channels. Sound amplitude monitored with time when deionised water passed through the microfluidic channel. b A photograph of an LIFS AC device with two in-plane PEDOT:PSS electrodes for monitoring the flow of human serum in a capillary channel similar in size to the human capillaries. Sound amplitude monitored with time when the serum passed through the capillary. c A photograph of an LIFS AC device with two in-plane PEDOT:PSS electrodes for monitoring two different liquids in a microfluidic channel. Alternating flows of deionised water and mineral oil were developed with two injection systems. The characteristic sound amplitudes for deionised water and mineral oil were precisely monitored with time. All the devices were operated at the AC frequency and voltage of 20 kHz and 100 V, respectively

Article Snippet: PEDOT:PSS (Clevios PH 1000), Zonyl surfactant (FS-300 fluoro-surfactant), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich.

Techniques: Injection