Introduction to galvanic electrolysis

The Elysis DC platform

Safety guidelines

Galvanic electrolysis is a relatively safe technique if practiced cautiously. It is possible to get bad outcomes, especially when practicing incorrectly, but there is also some irreducible risks as with any procedure.

The following are possible negative effects of electrolysis:

• Permanent scars, skin pitting ("raised scars" and "icepick scars"): overinsertion of the needle (pushing the needle in the skin past the end of the hair follicle) leads to deposition of hydroxide in the dermis, with subsequent tissue destruction. This leads to dermal scaring that can be raised or sunken. The extent of the scaring depends on the dose and individual scaring sensitivity. Scaring might get aesthetically better with time, but is mainly permanent.
• Hyperpigmentation, discoloration ("dark blotches", "lighter patches", "red patches"): during the healing period of the skin, and in particular if the dosage are excessive, or the skin is exposed to UV (including from the sun), a local change in pigmentation of the skin can occur. This pigmentation is likely to decrease with time (~months to year) but may persist to some level permanently.
• Skin marking ("iron tatoo"): if polarity is inversed (connecting the needle to the positive terminal despite the color coding), the metal of the needle will progressively be deposited in the skin, leaving dark marks around the hair follicle like a tatoo. If combined with needle overinsertion, risk of permanent marking is high.
• Skin infection, sepsis, death: bad infection control practice, such as not disinfecting the skin and the needle can lead to skin infection. Skin infections can progress to necrosis, sepsis and death. Sharing electrolysis needle between people can lead to transmission of blood borne infections, including HIV or hepatitis C.

These risks are the risk of electrolysis hair removal in general, whether DIY or performed by a professional. However, DIY electrolysis has increased risks compared to going to an electrologist, because your are learning as you go and lack experience. Proceeding in a cautious manner, and following the strategies laid below will help avoiding bad outcomes, but ultimately there is an irreducible amount of risk that you are taking.

Designating a practice area

Choose a part of your skin that is easily accessible, in which you will practice electrolysis technique. A typical zone could be your inner calf, between the ankle and the knee. You should accept that this zone might end up with some scaring or pigmentation - when starting, it is highly possible that you will make mistakes, hence a low-salience skin zone is indicated.

Assessing negative outcome

The state of the skin immediately after electrolysis is not final: the destruction of the follicle leads to inflammation that causes redness, swelling and possibly clotting in the follicle, even if perfectly performed. The condition of the skin will get better in 1 to 2 weeks, after which possible negative outcomes can be assessed.

A handful of follicle scaring or hyperpigmenting is highly unfortunate, but has limited visibility given skin is not uniform (moles, pores, texture). However, tens to hundred follicles having bad outcomes, especially if locally close and on a high-salience zone like the face, is catastrophic.

Thus, given that we cannot immediatly judge the results of a session, and we want to minimize the worst case consequences:

• When starting to treat a zone, treat 2-3 follicles the first time as a test, and assess results after two weeks
• After this, refrain from treating many follicle at once, especially concentrated locally, even with previous good result. Space the sessions out.
• Be especially cautious on high saliency area (mainly, face).

Treating people other than yourself

By doing electrolysis on yourself, you are the one making decisions, taking risks and bearing the possible consequences. You know what experience or lack thereof you have. This is an ethically clear situation. Doing electrolysis on other people when you are not experienced is clearly not ethical. Even if you suceeded on yourself, individual variability might lead to worse outcomes even if practising exactly as you had. Do not do it.

Dose calculation and recommendation

Dose from current and time

Typical dose for different hair types

You might come across the non-standard "unit of lye" in electrolysis textbooks and parlance. Here is the conversion to SI units:

1 "unit of lye" (uLye) = 0.1 mA in 1 second = 0.1 mC (millicoulomb) = 100 uC

From: (Godrey S., Principle and Practice of Electrical Epilation)

Progressive electrolysis

You can use progressive electrolysis to determine more precisely the necessary dose for a given hair type in a given region. This consist in delivering a base dose (given by the lower range of the recommended dose for the hair type, see above), then alternating between softly pulling on the hair using tweezers, and delivering increment of dose (~500 uC). The tweezer should not touch the needle during dose delivery, to not create a second current path. Ideally, the needle stays in the follicle while pulling on the hair.

The dose

Source for the hardware

ELysis DC+RF v1.1

Fixes some issues with v1.0, notably the ESD protection, but keeps most of the DC part. Also adds possibility to use HF thermolysis (not quite there yet - breakout board protyping).

• Kicad project files
• PDF schematics
• Gerbers
• Might need to add the library in Kicad_libs_v1.zip, below, from the v1
• PnP files for JLCPCB: bom_filtered.csv, Project_DCElysis_v1.1-top-pos_prepped_1.csv in the Kicad project archive. Need to manually switch most of the IC and diode in the JLCPCB SMT wizard thingy.

• LCD (option: 3.3V, 4-wire SPI, capacitive touch screen), with a 40-pin FFC (1mm pitch)
• Banana plugs
• Holes are for M3 (brass) stand-off, including for LCD mount (e.g. those)
• Audio jack is TRRS SMD socket (e.g. those)
• BNC post (e.g. those)
• SMA right angle (e.g. those)

ELysis DC v1.0

Main component list with some comments:

• Microcontroller: Raspberry Pi Pico (non-wifi), soldered-on. 3.3V buck converted used to power logic level
• Current DAC: AD5420, a SPI controllable, high resolution current source Digital-to-Analog converter. Good ESD resistance.
• Current Sensing: INA219, not so high resolution high-side current sensing from shunt resistor. i2c interface, convenient because amplified and ADC integrated, with high common mode voltage tolerated
• Connectors: BNC for connector with well-defined directionality (important that + and - are not switched accidentally). Jack for trigger - not ideal (could connect to actual audio device with unknown result) but common connector and cable

Project files:

• Kicad project files (has the electrolysis_board_lib.lib that defines important symbols, and Project_DCElysis_v1.pretty for footprint)
• Kicad library for various parts used in the v1 in addition to electrolysis_board_lib.lib
• PDF schematics

Known issues:

• Suboptimal routing of the 5V USB to the LEDs (see large trace on backside going through the through hole for the MCU). Possible fix: rerouting to go through the middle, going SMT only for the MCU
• ESD prot on the jack is not very good. Will redesign especially avoiding R29 which is stupid with hindsight.

Needle holder v1.0

The PCB holder is pretty bad because the weight of the cable is leveraged to the fingertips. Recommend solution below, while redesigning the whole holder assembly.

Needle holder: Makeshift

Get a banana jack receptacle, trrs jack receptacle and broken-down terminal block contactor (strip the plastic, you get the hole+screw thingy inside, and either solder to the post or use a strap wire with the needle in the terminal block) and make your own. Stress relief the cable by wrapping a loop around your wrist. I still use the PCB holder to plug the jack and trigger button, and stick it to the mirror I use for self-work (LED blinks when dose delivered, push button with the last 2 fingers of the free hand, first 3 used to angle and slightly stretch)

Source for the firmware

Available on the [gitlab]

Pre-alpha firmware (C++)

Git branch `prealpha`. C++ firmware with limited functionality, based on the breadboard prototype FW. Fixed dose set in the source code. Uses the RPico SDK - see the CMakelist.txt

Firmware for v1.1 hardware (DC+RF) (C)

Git branch `mainboard_v1_1`, see also `rfboard_v1_1` for the HF daughterboard.

Firmware v1.0 (Rust)

Maybe rewrite-it-in-rust later (shamefully failed to get anywhere fast so went back to usual)

Source for the (host) driving software

There is the possibility to drive the platform through the USB. It is optional, so that it is possible to use the ELysis from a simple USB charger or powerbank, but it allows finer control and data collection for research purpose.

Future plans

Replace the LED, small screen, and possibly the physical button, with a LCD with touch screen.

Make the holder setup much better. Probably 3D printed needle holder, and a wristband as intermediate between the cabling and the needle holder, to relieve the weight and keep things agile. Also need better triggering mechanism than a (semi stiff) pushbutton.

Revise the ESD prot setup.