A microfluidic device for non-invasively and passively accessing interstitial fluid from a patient includes a substrate containing multiple vertical micro channels therethrough, wherein at a first end of each of the multiple vertical micro channels a microheater is formed for controllably ablating a portion of dry dead skin cells to access the interstitial fluid； and wherein at a second end of each of the multiple vertical micro channels is a horizontal micro channel for receiving accessed interstitial fluid from a vertical micro channel and guiding the accessed interstitial fluid to a common collection port.
