The needle must penetrate the skin and the vein in the same place.

针头必须在同一处同时穿透皮肤和静脉。

youdao

One challenge is that laser light cannot penetrate the skin very deeply.

其中一个挑战是激光无法深入人的皮肤。

youdao

Tritium emits a weak form of radiation that does not travel very far in the air and cannot penetrate the skin.

氚发出的辐射很弱，在空气传播不远，不能穿透皮肤。

youdao

The recording electrodes can be carried by a skull cap, and nothing has to penetrate the skin.

ECONOMIST: Bionics (I)

It is unclear whether the antioxidants in grapeseed oil penetrate the skin sufficiently to benefit the skin, dermatologists say.

WSJ: An Oil's Promises, From Cooking to Cosmetics

Efforts to make the particles smaller have worked, but have raised safety concerns because they can penetrate the skin and potentially interact with cells.

WSJ: European Sunscreen Roadblock on U.S. Beaches