We present a method for the fabrication of ultra-smooth (0.2 nm RMS), aluminum substrates through template stripping (TS). The method relies on the use of mica as a template in combination with thermal evaporation of Al at high (>10 nm/s) rates under vacuum (≤1 × 10–7 Torr). As a reactive metal, Al is usually not considered a viable option for TS off oxide templates. However, under these conditions, the adhesion between the Al film and mica is poor, enabling the removal of the template under water without any mica residue. We verify the absence of mica using atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. We establish the suitability of these films for surface forces measurements. Multiple-bean interferometry in transmission yields high quality fringes allowing for the measurement of force–distance curves. The adhesion the films to mica is significantly higher than the adhesion of thermally evaporated Al (0.9 nm RMS). Preliminary results suggest that the TS-Al surface displays a higher corrosion resistance. The fabrication method will enable important experiments on this widely used material.

We investigated the carboxylated conjugated polymer poly 3-(3-carboxypropyl)thiophene-2,5-diyl as a nanosized (200−350 nm) biomolecule receptor layer on the channel of organic electrochemical transistor (OECT) devices. Myelin basic protein, SARS-CoV-2 spike glycoprotein S1, and their antibodies (10 nm size scale) were alternately used in the attached molecule form as receptors and analytes. Sub-ng detection in buffer was observed, and response to S1 was also obtained in clinical serum. Changes in threshold voltage and current output from OECT transfer curves and measurements of open circuit potential between receptor layers and a reference electrode provided complementary responses and insight into the response mechanisms, guiding further development of electrochemical field-effect and voltammetric protein sensors based on polymeric active layers with nanoscale functionality.

Multidentate hydrogen-bonding interactions are a promising strategy to improve underwater adhesion. Molecular and macroscale experiments have revealed an increase in underwater adhesion by incorporating multidentate H-bonding groups, but quantitatively relating the macroscale adhesive strength to cooperative hydrogen-bonding interactions remains challenging. Here, we investigate whether tridentate alcohol moieties incorporated in a model epoxy act cooperatively to enhance adhesion. We first demonstrate that incorporation of tridentate alcohol moieties leads to comparable adhesive strength with mica and aluminum in air and in water. We then show that the presence of tridentate groups leads to energy release rates that increase with an increase in crack velocity in air and in water, while materials lacking these groups do not display rate-dependent adhesion. We model the ratedependent adhesion to estimate the activation energy of the interfacial bonds. Based on our data, we estimate the lifetime of these bonds to be between 2 ms and 6 s, corresponding to an equilibrium activation energy between 23k B T and 31k B T. These values are consistent with tridentate hydrogen bonding, suggesting that the three alcohol groups in the Tris moiety bond cooperatively form a robust adhesive interaction underwater.