PDES-01DM User Manual
version 1.3
page 7
3. PDES System
3.1. System Description
Pressure ejection is a convenient method for applying both ionic and non-ionic solutions from
micropipettes. This method is popular for two reasons. First, it can apply to almost all solutions.
Second, the amount of solution ejected can be monitored by viewing the tip of the micropipette
under a microscope.
npi PDES units are designed for pressure ejection of drugs in physiological and
pharmacological studies. PDES systems can be equipped with high pressure outputs (up to P
max
= 4 bar / 58 psi) for drug application with fine-tipped micropipettes or with low-range pressure
output (P
max
= 0.7 bar / 10 psi) for controlled droplet application from large-tipped pipettes.
The PDES-01DM is a system with P
max
= 4 bar (58 psi) or 2 bar (29 psi). The device is designed
as a module for the npi EPMS-07 system. It comprises of one channel consisting of a precision
pressure regulator, an electronically controlled valve, (or a very fast micro valve located in the
micro
JECT), an analog timer and a digital pressure display. Ejection of drugs can be activated
manually or via a TTL input.
Mode of operation and timing is selected by controls at the front panel. If the internal timer is
used, the eject time is preset by a control and the time base can be selected by a toggle switch.
The operational status is indicated by a red/green LED.
The pressure connectors are also located at the front panel of the instrument. The injection
channel is equipped with an INPUT coupling where the pressure source is connected, an OUT
coupling where the injection pipette or the
micro
JECT headstage, respectively, is connected,
and an EXHAUST coupling where a low "retain" pressure can be applied in order to avoid
capillary effects at the tip of the injection pipette (analogous to the "retaining" current used in
iontophoretic systems). This pressure must be generated by an additional pneumatic device.
Please contact npi electronic for details. Systems with
micro
JECT are additionally equipped
with a connector for controlling the micro valve inside the
micro
JECT.
The injection pressure is preset by a precision pressure regulator. The pressure is displayed on
an digital manometer. Additional pneumatic devices (tubes, fittings, connectors, filters etc.) are
available. Please contact npi electronic for details.
A calibration procedure allowing quantitative drug application is described by Hofmeier and
Lux (1981), (see chapter 5).
3.2. PDES-01AM Components
The following items are shipped with the PDES-01AM system:
Pressure controller module for the EPMS-07 system
User manual