Emission biomimicryMimicking ejaculation is not a common feature in sextech. Tubes inside toys are not uncommon, but they're typically only hooked up to a syringe for manual use.
A design has been published on a forum previously using air pressure in a modified soda bottle, along with a programmable valve, to drive a cylinder full of fluid to be expelled. Since the pressure decreases each time the valve is pulsed open, this design has a neat feature built-in - a natural decay of the expulsion force. However, this design is not meant to be realistic in terms of emission volume.
I have a very different design that uses a peristaltic pump and a pinch valve. The pump runs while the valve is closed to build up the required head pressure in the tube, then the valve opens for the required effect. Decay of the emission force can be achieved by controlling the pump. There are two areas of development that need work here:
- The storage of fluid- currently, there is none except a cup with a tube in it. Design considerations include:
- Temperature- safe, active heating to maintain ~100 F temperature is critical
- Ease of filling
- Ease of empyting / cleaning
- The pinch valve. The current design uses an SG92R servo, a very common servo that is annoyingly loud. The pinch valve design itself is based on this concept on Hackaday. My current design is half-baked and needs to be designed properly from scratch- although it works enough as a proof of concept. The good folks over at Kinky Makers have suggested a small linear drive, like those used in CD players, might be just the thing for this pinch valve.
The peristaltic pump is rated 12 V, 5000 RPM, flow rate "up to 100 mL/min." I used this one from Amazon, powered with a 12 V supply and controlled with an arduino and a relay. The pump runs fluid down 2mm ID, 4mm OD food safe silicone tubing.
The pinch valve comes after the pump. When the valve is closed, it prevents all fluid flow.
The software is written so that each pulse opens the valve for 200 ms before closing it again. (Of course, the movement of the servo takes some amount of time here as well, but not much.) The pump is left on continuously. The timing between the pulses starts at 0.6 seconds, and increases 0.1 second with each pulse. This regime is taken from an Archives of Sexual Behavior paper. In both gifs on this page, the total is 5 mL simulant in 9 pulses.
The composition of the fluid, its cohesiveness and viscosity, play a role in the properties of how the fluid comes out of the tube. Different behavior between 'trickle' and 'spurt' should be able to be achieved by varying the valve and pump behavior. I have not yet experimented with the valve in any position other than fully open or fully closed, but there is room for variance there as well.