In vivo methods are provided for using an electric field to delivery therapeutic or immunizing treatment to a subject by applying non-invasive, user-friendly electrodes to the surface of the skin. Thus, therapeutic or immunizing agents can be delivered into cells of skin for local and systemic treatments or for immunization with optimal gene expression and minimal tissue damage. In particular, therapeutic agents include naked or formulated nucleic acid, polypeptides and chemotherapeutic agents.

A device for the transdermal delivery of a therapeutic agent to a biological subject that includes a first electrode comprising a first array of electrically conductive microprojections for providing electrical communication through a skin portion of the subject to a second electrode comprising a second array of electrically conductive microprojections. Additionally, a reservoir for holding the therapeutic agent surrounding the first electrode and a pulse generator for providing an exponential decay pulse between the first and second electrodes may be provided. A method includes the steps of piercing a stratum corneum layer of skin with two arrays of conductive microprojections, encapsulating the therapeutic agent into biocompatible charged carriers, surrounding the conductive microprojections with the therapeutic agent, generating an exponential decay pulse between the two arrays of conductive microprojections to create a non-uniform electrical field and electrokinetically driving the therapeutic agent through the stratum corneum layer of skin.

A medical device includes a sensor that is configured to measure a property of an outer layer of an anatomical body surface. The sensor includes a source probe configured to stimulate a local surface of the outer layer of an anatomical body surface. The sensor also includes a detector configured to measure a response of the outer layer resulting from the source probe stimulation. A controller coupled to the source probe and the sensor drives the source probe using a tailored stochastic sequence and determines the property of the outer layer using the measured response received from the detector. The sensor can be used with medical devices, such as drug delivery devices including microneedle transport devices and needleless injection devices.

An injector includes a housing having a chamber for holding a liquid formulation of an active principle to be injected into a biological body and an output port in fluid communication with the chamber through which the liquid formulation is injected. A piston is positioned within the housing, and includes an end portion with substantially the same shape as the chamber. A magnetic force draws the piston and housing together to expel the liquid formulation out of the chamber through the output port.

The invention provides a method of transferring in vivo a molecule into a striated muscle cell. More specifically, a method of the invention comprises contacting in vivo a striated muscle cell with a molecule, and electrically stimulating the muscle cell with one or more unipolar pulses of an electric field intensity ranging from 1 to 800 V/cm.sup.2. In one embodiment, the molecule is a nucleic acid encoding a protein of interest. For example, the invention provides methods of promoting angiogenesis and hemostasis.