For the last several years, we have been developing and characterizing “mobile” micro- and nano-instruments for use on-site (e.g., in the field). Although such portable, battery-operated instruments are much smaller that their laboratory-scale counterparts, sometimes they provide comparable performance and they often offer improved capabilities. As such, they are expected to cause a paradigm shift in classical chemical analysis by allowing practioners to “bring the lab (or part of it) to the sample”. Two classes of examples will be used as the means with which to illustrate the power of micro- and nano-instruments. One class involves a “patient” as the sample and an ingestible capsule-size spectrometer used for cancer diagnosis of the gastro intestinal tack as (part of) “the lab”. The other involves the “environment” as the sample and a portable, battery-operated, miniaturized instrument that utilizes a PalmPilot™ with a wireless interface for data acquisition and signal processing as (part of) “the lab”. To discuss how to electrically power such miniaturized instruments, mobile energy issues will be addressed. Particular emphasis will be paid to current or anticipated future applications and to the paradigm shifts that may prove essential in powering the next generation of miniaturized instruments.