The HSPC-1 is the only commercially available device for executing pressure-clamp protocols for studying mechanosensitive channel gating. It is entirely compatible with existing patch amplifiers, headstages and electrodes holders, and delivers pre-programmed pressure changes to cells during conventional voltage-clamp recording in the whole-cell configuration.
The HSPC-1 is the only commercially available device for executing pressure-clamp protocols for studying mechanosensitive channel gating. It is entirely compatible with existing patch amplifiers, headstages and electrodes holders, and delivers pre-programmed pressure changes to cells during conventional voltage-clamp recording in the whole-cell configuration.
The High Speed Pressure Clamp (HSPC-1) device is a closed loop pressure-control servo optimized to deliver vacuum and pressure at zero average flow. Although the device is targeted at patch clamp applications, response characteristics are fully adjustable for use in other experimental environments. It features a steady state pressure range of ±200 mmHg, hardware to prevent water entering the control valve, an external command input and a buffered output pressure monitor. Command response has been optimized for steps as large as +/-200 mmHg. Pressure rise time is amplitude dependent and varies from 5 ms for a 50 mmHg step to 15 ms for a 200 mmHg step approximately. Fall time is also amplitude dependent and varies from 5 ms for a 50 mmHg step to 15ms for a 200 mmHg step approximately. There is an amplitude independent delay of 325 µS on both the rising and falling edges of the response. System noise measured at the pressure sensor output is 0.275 mmHg RMS (5.5 mV RMS). Noise is primarily acoustic, arising from turbulent airflow through the valves, with a small 60 Hz component from the pressure pump. Noise levels fall to 0.037 mmHg RMS (740 µV RMS) when the pumps are turned off.
Unit Description
The HSPC-1 consists of three separate components:
The headstage, HSPC-Valve, is contained in a small aluminum box. It contains the pressure/vacuum
control valve, the pressure sensor and its associated instrumentation amplifier,
and the "water in line" sensor. If water enters the valve inlet line, this
sensor locks the control unit into a positive pressure "alarm" condition,
thereby expelling the water from the line and protecting the valve unit
from contamination.
The headstage, HSPC-Valve, is coupled to the control unit with a DB9 plug, and to the pumps with a pair of quick-connect air fittings. Two pneumatic ports are provided on the headstage. One of these is the output from the pressure/vacuum control valve. The other connects to the reference inlet on the pressure sensor. Output pressure will follow pressure (or vacuum) applied to this port. This can be used to apply suction by mouth when forming patches.
The control unit contains all of the necessary electronics to form a classical proportional-integral-differential feedback architecture, along with a power supply and high voltage amplifier to drive the piezo element in the pressure/vacuum control valve. Front panel controls are provided for setpoint adjustment, sensor zero pressure, alarm toggling and power on/off. A 3½ digit LCD display provides pressure readout to 0.1 mmHg resolution. Rear panel connectors are provided for a command input, a pressure monitor output, the headstage input, AC power for the pumps, and AC line power.
The optional
pressure/vacuum source, PV-PUMP, is made up of a pair of resonant piston pumps. Compressed
air and vacuum are routed into canisters that serve as volume reservoirs
whose function is to filter and stabilize the pressures. The pumps share
a common connection to the atmosphere through an in-line filter. This filter
removes dust and prevents contamination of the control valve and the pumps.
| Display | 4 1/2 Digit LED |
|---|---|
| Display Output Resolution | 0.1 mmHg. |
| Output Pressure | 200 mmHg |
| Power Input | 110-120VAC ~ 2A 220-240VAC ~ 1A 60/50Hz |
| Weight | 3 lbs. 14 oz. 0.85kg. |
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References
PV-Pump
Pressure/ vacuum pump for HSPC-1
| Ordering Information | |
|---|---|
| ALA HSPC-1 | High Speed Pressure Clamp - for stretch activated channels |
| ALA HSPC-Valve | High speed Piezo pressure/vacuum valve |
| ALA PV-Pump | Pressure/vacuum pump for HSPC-1 |