Pneumatics dispense with complexity

Scale down, however, and mechanical approaches to the displacement or dosing of micro-quantities of materials can become overly expensive, cumbersome and bulky. However, a device from Varta Microbattery appears to offer a new approach to the problem. This system, it is claimed, requires no electrical power supply and no springs, gears or other actuation components. Far cheaper and easier to implement than electro-mechanical or spring-loaded systems, it promises to open up a radically new approach to the design and assembly of small displacement devices. The displacement of small quantities of liquid, gel, paste or granules is required in many kinds of industrial and medical devices. It could, for instance, be used to apply lubricant to the internal parts of an industrial motor, or for dispensing medicine in intravenous drug delivery. When the amounts to be dispensed must be precisely controlled, a conventional mechanical solution will be expensive. This is because the highly precise machining and assembly of miniature mechanical parts is technically difficult to accomplish, and requires expensive manufacturing equipment. A device containing a micro-motor will also require a power source such as a battery, as well as the complex electronic circuitry required to regulate the power supply and to control the movement of the motor. The H2 cell from Varta, by contrast, is a tiny, gas-generating device. The same shape as a button (round) battery cell, it can generate a volume of pure hydrogen 270 times greater than its own volume. The V 130 H2 cell, for instance, is a button cell with an 11.5mm diameter, and a height of 5.4mm, equivalent to a volume of 0.55cm3. This tiny device can generate a volume of pure hydrogen of up to 150cm3. When activated, the cell releases hydrogen through two tiny holes in its upper face. It is activated by being short-circuited – connected to a resistor of a known value. The value of the resistance determines the rate of emission of gas – the lower the resistance, the faster the rate of gas generation. Until activated, the cell is dormant and releases no gas. When controlled by a resistor of fixed resistance value, the rate of gas emission is fixed. The resistance can, however, also be provided by a variable potentiometer, and this enables the user to adjust the rate of gas emission during operation. The rate is adjustable over a wide range, so the cell can be used over a period as short as some minutes and as long as one year. When placed inside a gas-tight housing and activated, the cell's release of gas generates pressure. In a device such as a syringe, this pressure will be converted into motive force. Hence an H2 cell can be used to drive a displacement device, and thus to dispense materials such as lubricants and medicines. A single V 130 H2 cell is capable of lifting a 10kg