The introduction of two-photon polymerization (TPP) into the area of Carbon Micro Electromechanical Systems (C-MEMS) has enabled the fabrication of three-dimensional glassy carbon nanostructures with geometries previously unattainable through conventional UV lithography. Pyrolysis of TPP structures conveys a characteristic reduction of feature size—one that should be properly estimated in order to produce carbon microdevices with accuracy. In this work, we studied the volumetric shrinkage of TPP-derived microwires upon pyrolysis at 900 °C. Through this process, photoresist microwires thermally decompose and shrink by as much as 75%, resulting in glassy carbon nanowires with linewidths between 300 and 550 nm. Even after the thermal decomposition induced by the pyrolysis step, the linewidth of the carbon nanowires was found to be dependent on the TPP exposure parameters. We have also found that the thermal stress induced during the pyrolysis step not only results in axial elongation of the nanowires, but also in buckling in the case of slender carbon nanowires (for aspect ratios greater than 30). Furthermore, we show that the calculated residual mass fraction that remains after pyrolysis depends on the characteristic dimensions of the photoresist microwires, a trend that is consistent with several works found in the literature. This phenomenon is explained through a semi-empirical model that estimates the feature size of the carbon structures, serving as a simple guideline for shrinkage evaluation in other designs.

Carbon nanomaterials play a vital role in biosensing applications in a wide variety of analytical devices due to their attractive electrochemical properties including relatively high electrical conductivity, wide electrochemical stability, biocompatibility, and chemical inertness. Biorecognition in electrochemical biosensing requires fine-tuning of the electrolyte/carbon interface resulting in the specific binding of the analyte and the measurement of the transduced signal. Successful protein immobilization on carbon nanomaterials can be achieved through surface functionalization methodologies that modify carbon from a naturally inert material to a physico-chemically active interface that can readily react with the analytes of interest. Any surface functionalization method influences electronical properties at the interface of the modified carbon thus interfacial signal transduction strongly depends on the type of surface modification. In this paper, we review the latest strategies for surface functionalization of carbon nanomaterials applied for covalent immobilization of different biomolecular entities. Furthermore, we summarize recently published techniques for carbon functionalization for achieving highly sensitive protein recognition. Some of these methodologies involve “multi-functionalization” of the carbon platforms enabling multiple biomarkers detection. Such advances in functionalization strategies open new windows of opportunity to the future of carbon as a biosensing material of choice.

Dielectrophoresis (DEP) is a powerful tool for label-free sorting of cells, even those with subtle differences in morphological and dielectric properties. Nevertheless, a major limitation is that most existing DEP techniques can efficiently sort cells only at low throughputs (150,000 cells min⁻¹) with 90% separation purity, 85% cell recovery, and no negative impact on cell viability.