May 2020

n LINEAR MOTION Linear actuators help to automate manual breathing resuscitators T he US linear actuator manufacturer Tolomatic has applied its expertise to develop is a new type of ventilator that uses an electric actuator to automate a type of manual resuscitator being used to fight the Covid-19 pandemic. The Ambu (artificial manual breathing unit) resuscitators – also known as bag valve masks or self-inflating bags – are non-invasive, positive-pressure resuscitators which provide oxygen to patients needing breathing assistance, mainly in emergencies when traditional ventilators are not available. The bag valve mask is placed over the patient’s nose and mouth, and the bag is squeezed to provide airflow via a combination of ambient air and an oxygen fed from a cylinder via a connecting tube. Squeezing the bag manually in this way is workable for short durations, but is not viable for longer-term care. It can also create air flow inconsistencies, and needs time and effort to stabilise the patient. Tolomatic’s approach has been to automate the manual process using electric linear actuators, thus allowing patients to continue getting air for days or weeks. The screw-driven linear actuators convert rotary power from a servomotor into linear motion. This provides smooth, consistent operation in which the velocity, acceleration and the distance of the movement can be controlled, allowing a more continuous volume of air per compression cycle and a more typical breathing cycle. Although Ambu bags have been automated using motors and single-direction cams or pneumatic actuators, these do not allow the stroke length to be varied – only the breathing frequency. As a result, the“tidal volume”of air flow to the patient is always the same, and the motion profile differs from a typical breathing cycle. The linear actuator system can change the frequency of the induced respirations as well as the volume. This is not possible using fixed- displacement rotary devices. The ability to control the motion of a linear actuator precisely allows a much more flexible air flow that could now be modified to suit a patient’s age, size or current needs. Actuators should also operate reliably for a long time and can incorporate alarms to warn of motor faults, and sensors to monitor the airflow quantity and quality. Within a week, Tolomatic developed a pair of actuator-driven resuscitators from concept design to the prototype stage. One is based on a rod-style actuator; the other is rodless. The company is hoping to spark interest from potential partners that could lead to the development of designs that could be submitted for approval. “We are not a medical device manufacturer and this design has not been approved by any regulatory bodies,”explains Andy Zaske, Tolomatic’s vice-president of sales and marketing.“However, many of our customers are, and our hope is that this might spark some interest in partnering with us on an approved final design solution.” n In less than a week, a US manufacturer developed a pair of machines that use electric linear actuators to automate the operation of resuscitators used to provide breathing assistance in emergencies when traditional ventilators are not available. One of Tolomatic’s two automated resuscitators is based on a rod-style screw-drive electric actuator • ATEX and IECEx certification for Gas and Dust • Extreme corrosion resistance: high grade stainless steel housing (1.4404) • Resolution up to 22 Bit Singleturn + 12 Bit Multiturn • High protection class up to IP66 / IP67 • Easy and fast field installation • Interfaces: BiSS, SSI and Profibus www.impulseautoma琀on.co.uk | tel: +44 (0)1264 364194 | ISO 9001 registered company AX73 Absolute Rotary Encoder for Hazardous Environments UK Official Distributor of Hengstler