We present a novel method, to our knowledge, for producing compact optical fiber delay lines (OFDLs) using single-mode fiber (SMF) wound on a 3D-printed spool. By applying a mass-based approach, the SMF length is accurately determined through a fiber mass–length correlation. Results demonstrate strong agreement between the OFDL length obtained via this mass method and traditional optical time-domain reflectometry. Additionally, the experimentally measured delay times align well with theoretical calculations, and the OFDLs show low insertion loss (<1 dB), including contributions from ferrule connector/angled physical contact (FC/APC) connectors. This method offers a simplified and potentially scalable solution for fabricating compact OFDLs. 

We have developed an optical fiber-based module that can select, retrieve, and transfer single cells, and cell clusters. Cell picking and isolation has several applications such as separating circulating tumor cells, isolating single fetal cells for prenatal testing, and others. Our Lab-in-a-Fiber (LiF) module can detect fluorescent cancer cells (MCF-7) from a mixture of labeled and unlabeled cells and pick them up for further analysis. The cells picked up by the fiber show a 90% survival rate on viability tests, making this cell-picking technique an attractive alternative to existing methods.