Right now no, an Arduino can't be sentient because it's not alive. If at some future point an Arduino could tick all the "is alive" boxes [0]: - homeostasis - organisation - metabolism - growth - adaptation - response - reproduction Then yes, there would be a good case for the Arduino being sentient.
However if you take a look at the list you'll see response is listed, that's because anything that is alive is sentient by definition.
Sentient by definition is really the point, sentient and sapient were defined specifically to codify the uniqueness of humanity.
All these other this are sentient, but only us, humans, and sapient.
The definitions although seemingly scientific are simply a re-enforcement of the biblical idea that the world was created for us, and that we can essentially do as we please, you can see this is the test for sapience, which is, is the specimen a member of the homo sapiens species.
Just for completeness, and to also touch on why this might become an important question; you'll also see organisation on that list. Organisation is usually defined as being made up of one or more cells, which suggests that an Arduino, or any machine, will always fail to pass that test.
Essentially humans have defined life in terms of itself. This makes sense, we only have a single reference and as such we can't even begin to imagine what other forms of life may exist.
However, as we create ever more complex nondeterministic machines, or if we ever get serious about finding extraterrestrial life, this definition is going to have to change to allow for other possibilities.
That's a historic misinterpretation of biblical teaching on the place of people on the world. Genesis 1 gives humanity dominion over the creation, but given that Genesis 2 parallels that command with the twin verbs, "tend and keep" (or sometimes "guard and defend"), the idea can't permit wanton destruction[1]. Rather, humans, made in the image of God the King, have a royal calling to work for the flourishing of life in all the earth.
We're called, not to do as we please, but to do what pleases the Creator. Thus, Proverbs speaks of the tender mercy of a righteous person towards his or her animals, and contrasts it with the cruelty of the wicked. Deuteronomy's rules for warfare forbid destroying fruit trees, for they're the means of sustaining life.
Historically speaking, many of the evangelical Christians who joined Wilberforce to campaign against British slavery also started the first humaine societies, anti-child-labor groups, and the first women's rights organizations.
The Bible calls humanity to compassionate care for all life, including plants, animals and unborn humans.
[1] Lynn White's essay, The Historical Roots of Our Ecological Crisis (1967. Science 155: 1203-1207), contributed to this idea that Christianity caused our ecological crisis. However, Francis Schaeffer's 1970 book in responce to White's essay, Pollution and the Death of Man, explains the Bible's actual teaching on humanity's calling to steward creation for God's glory.
And "responds to input" isn't really the same thing at all as "capable of feeling sensations" (though, like many definitions, the line between the two is fuzzy, hard to pin down, and possibly context dependent.)
Life itself is a notoriously tricky thing to define definitively.