Medical assembly design help

[Luci]

Hello ,
I have an medical device assembly, where I trigger the needle for injection, mechanically, with a pretensioned spring. Injection takes 3 minutes, then I have to retract the needle. How can I trigger the needle, using an electrical impulse ?

 

[AZFIREBALL]

How about this?

 

[Luci]

How about this?
View attachment 244672

Yes, nice proposal. But I don't understand how the solenoid is acting.
I need to trigger the needle retraction, at the end of injection, not immediately after the insertion.

 

[AZFIREBALL]

You will need a timer circuit to run the solenoid and motor at the proper times.
The solenoid holds the needle up until the time for injection. It fires...the needle goes down. The timer allows 3 min. then triggers the motor to retract the needle until it is again latched up by the solenoid.
Then the cycle starts all over again.

 

[berkeman]

Welcome to the PF.

Hello ,
I have an medical device assembly, where I trigger the needle for injection, mechanically, with a pretensioned spring. Injection takes 3 minutes, then I have to retract the needle. How can I trigger the needle, using an electrical impulse ?

What is the application? Can't you just use an IV infusion instead? Who is the patient, and what is the injected drug? Does it need to be an IM or subcu injection?

 

[Luci]

You will need a timer circuit to run the solenoid and motor at the proper times.
The solenoid holds the needle up until the time for injection. It fires...the needle goes down. The timer allows 3 min. then triggers the motor to retract the needle until it is again latched up by the solenoid.
Then the cycle starts all over again.

Motor is too expensive for my application.

 

[Luci]

Welcome to the PF.

What is the application? Can't you just use an IV infusion instead? Who is the patient, and what is the injected drug? Does it need to be an IM or subcu injection?

Needle insertion mechanism is mandatory. I fire the needle using a spring, the drug flows for 3 minutes and then I have to retract the needle. But without using a motor, witch is too expensive.

 

[JBA]

Is this a single shot operation or is it intended to deliver subsequent repeated injections automatically?

 

[berkeman]

Needle insertion mechanism is mandatory. I fire the needle using a spring, the drug flows for 3 minutes and then I have to retract the needle. But without using a motor, witch is too expensive.

You still didn't say what the application is. Keeping a needle steady in a patient for 3 minutes is quite a chore, unless it's an IV tube. Why are you giving an IM injection that takes 3 minutes?

 

[AZFIREBALL]

Motors like this on Ebay for $1.99 each. Too expensive? How much have you budgeted for this project?

 

[berkeman]

Thread closed temporarily. @Luci -- You need to send me a message explaining what you are trying to do before this thread can be re-opened. Click on my avatar picture and select "Start a conversation". Thank you.