Such valves are used to adjust and modify the volume flow of a fluid through a fluid channel. It is known in this context that the flow of the fluid through the channel is to be controlled by exerting pressure from the outside on a tube in which the fluid channel is formed, such that the pressure is adjusted as a function of a desired volume flow of the fluid through the channel.
In medical technology, dosing of volume flows takes place, for example, through microvalves or directly through a corresponding pump with which the fluid to be dispensed is acted upon with pressure. Valves are used in medicine and in the cosmetic field, for example, in injection of medically and cosmetically active substances. In addition to the injection of substances for fat reduction or for injection beneath wrinkles, dosed dispensing of a substance is also necessary for application of ink for tattooing or permanent makeup in the cosmetic field. In addition to various vaccinations, medical applications also include, for example, mesotherapy. In these applications, in addition to the simple application of the media, simultaneous administration of multiple media is also provided, so that the media react with one another only after being applied.
The dosing of the fluid may be performed by means of a contact method or a noncontact method. The fluid-dispensing device thus either does or does not come in contact with the skin. Noncontact devices are also referred to as so-called dispensers. The process of delivering the fluid is itself known as dispensing, jetting or pulsing. This dosing serves to apply substances to the skin or in subsequent substance delivery systems (cf. EP 1 882 491, for example). Contacting may be understood as dosing onto or through a surface.
All these applications have in common the need for accurate dosing. Problems are often presented by chemical or fluid properties or particles or variable media.
The document DE 103 37 484 B4 describes a noncontact dosing system, in which a tube is squeezed at a high speed, so that a free-flying droplet of liquid is formed. Dosing frequencies of 50 Hz may be achieved in this way. The design here is an open system without a prepressure. The liquid fills the tube because of the capillary forces, but the maximum dosing quantity and dosing frequency are limited by this design. If there is a backpressure, functioning is very limited or impossible.
The document DE 693 25 591 T2 describes valve system for switching a flow through flexible tubes. Two positions (bistable open/closed) are selected via a pivotable lever. The liquids should flow through the valve at the coupled flange of this construction, which is manufactured by casting and welding. Possible contamination of the liquid is not prevented, nor can this principle be used as a disposable part or for higher frequencies (>1 Hz).
The document EP 1 699 560 B1 describes one possibility for pipetting extremely small quantities, but is based essentially on a combination of traditional pipetting systems and the known PipeJet method, i.e., a tube deformation, embodied in this case as a pipette tip. It is thus possible here to dose only extremely small particles which fly through the air to their destination. This method cannot be used for injections because it is impossible to work at a backpressure.
The document DE 197 06 513 C2 describes a micro-dosing method based on a pressure chamber having a reservoir connection and a fluid outlet. The pressure chamber is reduced in size by a displacement mechanism, so that the fluid is forced to the outlet. A device for detecting the position of the displacement mechanism is essential here.
The document US 2010/0030152 A1 describes a therapeutic micro-needle system, in which multiple cannulas are used instead of one cannula.