Nicolaas Petrus Willard

I-line lithography of poly-(3,4-ethylenedioxythiophene) electrodes and application in all-polymer integrated circuits

Industrialization of polymer electronics requires the use of safe solvents. To that end an I-line lithography process for conducting thin poly(3,4-ethylenedioxythiophene) films has been developed. The fully waterborne process is based on photocrosslinking using bisazide- and polyazide-type photoinitiators. The minimum feature size realized comprises 2.5 μm wide lines separated by 1 μm spacings. The sheet resistance is 1 kΩ/square. The process has been applied to fabricate all-polymer integrated circuits. The technology is demonstrated with functional 15-bit code generators.

Ultrasound contrast agents for molecular imaging

The successful use of targeted ultrasound contrast agents (USCAs) for qualitative US-based imaging has been shown by several academic and industrial research groups in different animal models. Furthermore, techniques have been developed that enable the in-vivo quantification of targeted microbubbles (MBs). USCAs for quantitative functional and molecular imaging in small animals can be used for a more detailed characterization of new and established disease models and provide quantitative biological insights into the interaction between drug and target or target and disease in living animals. The advantages of such contrast agents in research and development are seen to be as follows: new functional or molecular findings in the complex biology of disease development, these findings can lead to new therapeutic strategies or drug candidates, a better understanding of the treatment effects of new and existing drug candidates, a more sensitive and specific characterization of early treatment effects in living animals, identification of in-vivo biomarkers for translational medicine. Further outcomes are seen in speeding up the evaluation of new drug compounds and in a reduction of the number of animals used for biomedical research.

Photocrosslinking of ferroelectric polymers and its application in three-dimensional memory arrays

An I-line photolithography process for ferroelectric polymers is developed. It is based on photocrosslinking using a bisazide photoinitiator. Patterned layers were realized down to 1-2 µm resolution. Crosslinking yields a close-to-insoluble ferroelectric polymer network that counter intuitively has similar ferroelectric properties as a noncrosslinked film. The negative process is used to stack ferroelectric films on top of each other to make three-dimensional cross-bar arrays of nonvolatile ferroelectric capacitor memories.

Water based I-line projection lithography of PEDOT

Structured conducting thin layers of poly(3,4-ethylenedioxythiophene) (PEDOT) have been made by photosensitizing a PEDOT latex which is stabilized with polystyrene sulphonic acid (PSS). The process is based on waterborne solutions only and makes use of negatively acting, highly sensitive, lithography with UV light of 365 nm (I-line). The minimum feature size obtained is 1 μm spacings and 2.5 μm lines with a sheet resistance of about 1 kOhm/square. The environmentally acceptable technology has been demonstrated with functional all-polymer integrated circuits prepared on 150-mm wafers.