You can see the following:

Article 3D printing of polymer matrix composites: A review and prospective

Article Recent advances in 3D printing of biomaterials

Conference Paper About the Use of Recycled or Biodegradable Filaments for Sus...

https://www.polymersolutions.com/blog/biodegradable-3d-printing-materials-and-bone-fractures/

http://www.mdpi.com/1420-3049/21/5/539/pdf

https://3dprint.com/tag/biodegradable-filament/

https://3dprint.com/12601/3d-printing-biodegradable/

Hi Magdalini,

Although it might not be the best answer, I wanted to highlight a few techniques which you might find useful. Just like you have mentioned, conventional 3D printing approaches, essentially give you resolutions down to a few microns. (FDM is the one of the most popular additive manufacturing tehniques while stereolithography can give you very good resolution).

Melt electrospinning writing (MEW) is a technique which draws inspiration from the usual electrospinning (ES) and additive manufacturing (AM) techniques i.e. it gives you better control over the fibre diameter (characteristic of ES) but at the same time it gives you control over the guided deposition of fibers while printing a complex geometry/scaffold just like a 3D printer, unlike the usual electrospinning process where the fibers are deposited in a random/unaligned fashion. I am not sure but have read articles, which mention that - by playing with the parameters like high electric field, low flow rate, low diameter spinneret etc., sub-micron level fiber diameters are achievable. I am attaching an abstract that I had found sometime back where polycaprolactone (PCL), a very popular biodegradable polymer has been extruded using MEW.

https://fenix.tecnico.ulisboa.pt/downloadFile/1407770020544843/MELT%20ELECTROSPINNING%20FOR%20THE%20PRODUCTION%20OF%20OSTEOCHONDRAL%20SCAFFOLDS%20WITH%20FUNCTIONAL%20AND%20COMPOSITIONAL%20GRADIENTS.pdf

You might also be interested in learning about the near-field electrospinning technique.

Article Near-Field Electrospinning

Hope that helps!!

Goran Schmidt

Srujan Singh I believe near-field electrospinning is the closest method to what I'm looking for.. Thank you for the other suggestions, too!

Md. Abdur Rahman Thank you very much for the bibliography! Some methods indeed go to sub micrometer resolution but cannot be precisely controlled (e.g. for aligned fibers)