According to some embodiments, a syringe may include a barrel； a delivery conduit； a plunger seal disposed within the barrel； and a plunger rod assembly affixed to an end of the barrel, the plunger rod assembly including a first plunger rod component comprising a first linear gear, a second plunger rod component disposed at least partially in the barrel and engaged with the plunger seal, wherein the second plunger rod component comprises a second linear gear, a first rotational gear having a plurality of gear teeth for engaging the first linear gear, and a second rotational gear having a second plurality of gear teeth for engaging the second linear gear, wherein the first rotational gear is coupled to the second rotational gear such that translation of the first plunger rod component causes translation of the second plunger rod component.根據某些實施例，一種注射器可包含：一筒管；一遞送導管；一柱塞密封件，其安置於筒管內；及一柱塞桿總成，其固定至筒管之一端，柱塞桿總成包含：一第一柱塞桿組件，其包括一第一線性齒輪；一第二柱塞桿組件，其至少部分地安置於筒管內且與柱塞密封件嚙合，其中第二柱塞桿組件包括一第二線性齒輪；一第一旋轉齒輪，其具有用於與第一線性齒輪嚙合之複數個齒輪齒；及一第二旋轉齒輪，其具有用於與第二線性齒輪嚙合之第二複數個齒輪齒，其中第一旋轉齒輪耦合至第二旋轉齒輪使得第一柱塞桿組件之平移致使第二柱塞桿組件平移。
